SHIPBOARD
ELE CTR I C AL SYSTEMS
NAVAL EDUCATION AND TRAINING COMMAND
NAVEDTRA 10864-D
/v;
PREFACE
This text is written primarily for junior officers of the U. S* Navy
and Naval Reserve as an aid in gaining more knowledge of the electrical
equipment and electrical systems installed aboard Navy ships. Repre-
sentative equipments and systems are described by the use of pictoral
views and block diagrams with electrical schematics being kept to a
minimum. The operating principles of any of the electrical or electronic
devices or circuits mentioned in the text may be found in Basic Electricity
and NAVPERS 10086-B or Basic Electronics. NAVPERS 10087-C.
Information relating to shipboard machinery other than electrical and
the organization and administration of the engineering department
is contained in Principles of Naval Engineering, NAVPERS 10788-B
and Engineering Administration, NAVPERS 10858~E
This text provides hints on managing the maintenance of generating
equipment, distribution systems, motors, controllers lighting systems,
degaussing systems, auxiliary equipment, alarm and warning systems,
ships indicating and dead reckoning equipment, telephone systems,
amplified voice systems and gyrocompasses. Safety precautions required
in maintenance and operation of the above equipment and systems are
stressed.
This text was prepared by the Naval Education and Training Program
Development Center, Pensacola, Florida for the Chief of Naval Education
and Training (CNET) personnel. Technical assistance was provided by
the Electrical Schools located at Great Lakes, IL, Norfolk, VA, and
San Diego, CA.
Stock Ordering No.
0502-LP-054-3250
Revised 1976
Published by
NAVAL EDUCATION AND TRAINING SUPPORT COMMAND
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON, D.C.: 1976
THE UNITED STATES NAVY
GUARDIAN OF OUR COUNTRY
The United States Navy is responsible for maintaining control of the sea
and is a ready force on watch at home and overseas, capable of strong
action to preserve the peace or of instant offensive action to win in war.
It is upon the maintenance of this control that our country's glorious
future depends; the United States Navy exists to make it so.
WE SERVE WITH HONOR
Tradition, valor, and victory are the Navy's heritage from the past. To
these may be added dedication, discipline, and vigilance as the watchwords
of the present and the future.
At home or on distant stations we serve with pride, confident in the respect
of our country, our shipmates, and our families.
Our responsibilities sober us; our adversities strengthen us.
Service to God and Country is our special privilege. We serve with honor.
THE FUTURE OF THE NAVY
The Navy will always employ new weapons, new techniques, and
greater power to protect and defend the United States on the sea, under
the sea, and in the air.
Now and in the future, control of the sea gives the United States her
greatest advantage for the maintenance of peace and for victory in war.
Mobility, surprise, dispersal, and offensive power are the keynotes of
the new Navy. The roots of the Navy lie in a strong belief in the
future, in continued dedication to our tasks, and in reflection on our
heritage from the past.
Never have our opportunities and our responsibilities been greater.
ii
CONTENTS
CHAPTER page
1. Safety i
2. Power Supplies . 1;L
3. Distribution Systems 3i
4. Motors and Controllers . 53
5. Shipboard Lighting . . . 59
6. Degaussing o 93
7 Auxiliary Shipboard Equipment 118
80 Alarm and Warning Systems 137
9. Ship's Indicating, Order, and Metering Systems 159
10. Interior Communications Telephone Systems . . 193
llo Amplified Voice Systems o 227
12. Gyrocompasses . a 255
INDEX ..o.o 282
iii
CREDITS
The illustrations indicated below are included in this edition of
Shipboard Electrical Systems through the courtesy of the designated
55i^n7~liid publisher. Permission to use the illustrations are grate-
fully acknowledged.
Source Figure
General Electric Company 2-4, 2-5
VVestingbouse Electric Corporation 2-6, 2-7, 2-8, 2-9, 3-1, 3-2,
3-12
Woodward Governor Company 2-17
VA RO , Inc , Biom etric s Instrum ent
Corporation 2-20
Teledyne Inet 187.5 KVA, 150 KW,
60 Ha to 400 Hz Power Converter 2-22
ITE Circuit Breaker Company 3-10, 3-14, 3-16
Left Illustration ONLY, ITE Circuit
Breaker Company 3-11
Cutler Hammer Incorporated 4-12, 4-14
The Louis A His Company, Drives
and Systems Division 6-15
Gaibraith- Pilot Marine Division of
Marine Electric Railway Products
Division, Inc. 9-4
U. S. Instrument Corporation 10-5, 10-6
Strom berg-Carlson Corporation 10-27, 10-28
RCA 11-16, 11-17
Sperry Marine Systems 12-19, 12-20, 12-23, 12-24
IV
CHAPTER 1
SAFETY
In accordance with article 0712 of U.S. Navy
Regulations the commanding officer is vested
with the responsibility of safety aboard his ship.
In this regard, he is to ensure that all personnel
under his command are instructed in, and comply
with, applicable safety precautions and proce-
dures. While the commanding officer cannot
delegate his responsibility, he must necessarily
delegate authority to his officers and petty officers
to ensure that all safety precautions are under-
stood and, more importantly, enforced. As
Division Officers you will be required to thor-
oughly understand all safety notices and in-
structions and have your division or department
comply with them.
Some of your sources of safety information are:
Navy Safety Precautions for Forces Afloat,
OPNAV INSTRUCTION 5100.19 jNAVSHIPS' Tech-
nical Manual, Chapter 300; Electronics Instal-
lation & Maintenance Book (EIMB) General,
NAVSHIPS' 0967-LP-000-0100;HowtoKeep Elec-
tricity from Killing You, NAVSHIPS' 0981-LP-
052-8500; Electric Shock Its Cause & Prevention,
NAVSHIPS' 0900-LP-007-9010; Electric Shock
and Its Prevention, NAVSHIPS' 0283-LP-236-
0000; Safety Notes from NAVSEA Journal &
Ships Safety Bulletin; EM 3 & 2, NAVEDTRA 10546,
and Fathom Magazine published by Naval Safety
Center, Norfolk, You should be familiar with all
of these publications and ensure that your division
or department complies with their contents.
All safety information in this chapter is ex-
tracted from the above listed publications. The
information contained herein should be used for
general guidance and not as final authority*
ELECTRICAL HAZARDS
Probably more deaths aboard ship occur from
electric shock than from any other type of accident.
Prevention of electric shock aboard ship neces-
sitates strict compliance with all safety require-
ments pertinent to the various work areas as well
as strict adherence to all prescribed safety pre-
cautions for the type of job concerned,
ELECTRIC SHOCK
Flow of current through the body is the cause
of electric shock. Factors determining the extent
of the body damage which results from electric
shock are (1) the amount and duration of the
current flow, (2) the parts of the body involved,
and (3) the frequency of the current, if a.c.
In general, the greater the current or the longer
the current flows, the greater will be the body
damage,. Body damage is also greatest when the
current flow is through or near nerve centers
and vital organs. For example: If a 60-hertz
alternating current is passed through a man
from hand to hand, or from hand to foot, and is
gradually increased from zero, the following
effects will occur:
1. At approximately 1 milliampere (0.001
ampere) the shock will be perceptible
2. At approximately 10 milliamperes (0.01
ampere) the shock will be sufficiently intense to
prevent voluntary control of the muscles and the
man may be unable to let go or free himself
3. At approximately 100 milliamperes (0.1
ampere) the shock will be fatal if it lasts for
1 second.
High frequency currents have a tendency
to flow along the surface of the skin (skin
effect); persons coming into contact with these
currents usually suffer severe burns although
the current may not penetrate the body.
Two conditions must be present for an electric
current to flow through the body and cause elec-
tric shock.
1. The body or some part of the body must
form part of a closed circuit; and
SHIPBOARD ELECTRICAL SYSTEMS
2* Somewhere in the closed circuit there
must be a voltage, or a difference in potential,
to cause a current flow.
It follows, then, that to prevent electric shock,
you should always ensure that your body never
forms a part of a closed circuit.
Tests made by the National Bureau of Standards
show that the resistance of the human body may
be as low as 300 ohm s under unfavorable conditions
such as those caused by salt water and perspi-
ration. These test results indicate immediately
that it is possible for a potential difference
as low as 30 volts to cause the fatal 0.1 ampere
current flow through the body. It is true that the
conditions of the above tests were extremely
unfavorable,. However, the results leave no doubt
as to the dangers relative to the 120- volt circuits
aboard ship and as to the necessary precautions
that all personnel must observe continually.
Causes of Electric Shock
Practically all electric shocks are caused by
human failure rather than by equipment failure.
Equipment may suddenly fail and cause fatal
shock even if it were skillfully designed for
safety, thoroughly tested before use, and used
in accordance with applicable safety precautions.
This can happen, but rarely does. Nearly all
shipboard deaths due to electric shock have been
caused by human failure manifested in one or
more of the following ways:
1. Unauthorized use of, or unauthorized modi-
fications to, equipment.
2 Failure to observe the applicable safety
precautions whenusing equipment or when working
on or near energized equipment*
3. Failure to repair equipment which is known
to be defective and has previously given a mild
shock to user So
4. Failure to test and inspect equipment for
defects, or failure to remedy all defects found
by tests and inspections.
All of these failures may be summarized as
failure to observe applicable safety precautions.
SAFETY TRAINING
PROGRAM
The fields of electricity and electronics de-
mand an effective safety training program because
of the inherent hazards. Technicians working
with the electrical systems are generally aware
of the safety precautions but, due to familiarity,
sometimes "overlook" them. In this respect
a vigorous training program is not just a good
idea; it is a MUST.
There are many systems and plans to guide
you in implementing a safety training program.
You will find some excellent ideas in Standard
Organization and Regulations of the U.S. Navy,
OPNAVINST 3120 32 and in the Division Officers
Guide.
The training plan you select is not as important
as that you have a system and make it work to have
a safety-conscious division.
SAFETY REQUIREMENTS
As a division officer of the electrical depart-
ment aboard ship, you will be dealing with some
special tasks which are unique to the electrical
field. A basic understanding of these situations
will prove helpful to you in maintaining safety
precautions within the division,,
IN WORK AREAS
Safety requirements concerning the various
shops and other work areas aboard ship are
prescribed by the NAVSHIPS' Technical Manual
and other authority. The requirements for elec-
trical work areas include the following:
1. Rubber matting that meets military speci-
fications is to be provided in the front and rear
of all electrical switchboards including 1C and
weapons control switchboards. This rubber mat-
ting is also required in front of all announcing
system amplifiers and control racks, on areas
around electronic equipment, and in front of
test benches or tables in electrical and elec-
tronic shops. The matting should be cemented to
the deck except on grating and removable deck
plates.
2. HIGH VOLTAGE signs (fig. 1-1) and suit-
able guards are to be provided wherever the
voltage exceeds 30 volts in exposed live circuits
or equipment
3. All rear service switchboards are required
to have an expanded metal enclosure with a door.
The enclosure is NOT to be used as a storage
space. A safety poster, such as shown in figure
1-2, posted on the door might be agood reminder.
Chapter 1 SAFETY
HIGH
VOLTAGE
40.67(31)
Figure 1-1, High voltage warning sign.
4. First aid treatment (fig. 1-3) for electrical
lock and other applicable electrical safety
ecautions must be posted in all areas containing
ajor units of electrical or electronic equipments.
5. NO SMOKING signs are to be posted in
>aces where storage batteries are charged
id in all other spaces where explosive vapors
ay be present,
6. Workbenches must be insulated (fig. 1-4)
j prescribed by General Specifications for
lips of the U.S. Navy, NAVSHIPS' 0902-001-500.
warningplate which reads, ELECTRIC SHOCK
A.NGER DO NOT TOUCH ENERGIZED CIR-
LJITS must be installed over the workbench,
rtificial respiration instructions and a
ascription of an approved method (fig. 1-5)
reselling personnel in contact with energized
rcuits must also be posted.
i PORTABLE
LECTRICAL EQUIPMENT
Navy specifications for metal-cased portable
ols require that the electric cord for the tools
\ provided with a distinctively marked grounding
>nductor in addition to the conductors that
L PPty power to the tool. Past practice was to
\Q red for the grounding conductor in three-
inductor cables for portable tools and equipment
id green in four-conductor cables, except for a
w cases in which black was used in the cords
r some items of portable equipment. Revised
iecifications require that green be used for
e grounding conductor in cables for all new
40.67(67B)
Figure 1-2. Safety poster.
metal-cased portable tools and equipment. The
end of the grounding conductor which is within
the tool should be connected to the metal housing,
the other end should be grounded; that is, con-
nected to the ship's metal structure. To provide
a convenient means of connecting the grounding
conductor to ground, NAVSEA has standardized
the use of grounded- type plugs and receptacles
which automatically make this connection when the
plug is inserted into the receptacle.
Nonconducting case-type portable electric
tools (plastic-cased, shockproof) do not require
grounding cords or plugs. The two-conductor
cords and two-prong ungrounded connector plugs
furnished on these plastic-cased tools are accept-
able and can be inserted into blade-type recep-
tacles aboard ship which may be labeled
* 'WARNING: Insert 3-prong grounded plugs only,"
Before using portable electrical equipment
for the first time, check the plug connections of
the equipment for correct wiring. The test of
SHIPBOARD ELECTRICAL SYSTEMS
ARTIFICIAL RESPIRATION
MOUTH-TO-MOUTH OR MOUTH-TO-NOSE
RESCUE BREATHING
PLACE CASUALTY ON BACK IMMEDIATELY
DON'T WASTE TIME MOVING TO A BETTER PLACE OR
LOOSENING CLOTHING.
QUICKLY CLEAR MOUTH AND THROAT
REMOVE MUCUS, FOOD AND OTHER OBSTRUCTIONS.
TILT HEAD BACK AS FAR AS POSSIBLE
THE HEAD SHOULD BE IN A "CHIN-UP" OR "SNIFF" POSI-
TION AND THE NECK STRETCHED.
/LIFT LOWER JAW FORWARD
GRASP JAW BY PLACING THUMB INTO CORNER OF MOUTH.
DO NOT HOLD OR DEPRESS TONGUE.
PINCH NOSE SHUT OR SEAL MOUTH
PREVENT AIR LEAKAGE.
OPEN YOUR MOUTH WIDE AND BLOW
TAKE A DEEP BREATH AND BLOW FORCEFULLY (EXCEPT
FOR BABIES) INTO MOUTH OR NOSE UNTIL YOU SEE CHEST
RISE.
LISTEN FOR EXHALATION
QUICKLY REMOVE YOUR MOUTH WHEN CHEST RISES. LIFT
JAW HIGHER IF VICTIM MAKES SNORING OR GURGLING
SOUNDS.
REPEAT STEPS SIX AND SEVEN 12 TO 20 TIMES
PER MINUTE
CONTINUE UNTIL VICTIM BEGINS TO BREATHE NORMALLY.
* FOR INFANTS SEAL BOTH MOUTH AND NOSE WITH YOUR
MOUTH
BLOW WITH SMALL PUFFS OF AIR FROM YOUR CHEEKS.
T) CLEAR THE MOUTH
AND THROAT
TILT HEAD BACK
AND LIFT JAW
PINCH NOSE
(OR SEAL LIPS)
B
Figure 1-3* Artificial respiration and cardiac massage.
4
4.224
Chapter 1 SAFETY
WORKING AREA (TOP, TOP EDGE, FRONT OF DOORS AND DRAWERS)
INSULATED WITH 3/8 INCH BENELEX 401
ALLOTHER EXPOSED METAL SURFACES IN THE WORKING AREA
(BENCH FRONT AND SIDES, KNEE HOLE SIDE, UNDERSI DE OF TOP)
INSULATED WITH 1/8 INCH BENELEX 401.
RUBBER MATTING, EITHER GREY OR GREEN BUTATLEAST
3 FEET WIDE.
77.308
Figure 1-4 Typical electric workbench.
portable equipment should be conducted in a
workshop equipped with a nonconducting surface
workbench and a diamond-tread, rubber deck
covering. Electricians making the tests should
wear rubber gloves during tests.
CONNECTING AND
DISCONNECTING
SHORE POWER
Because of the variety of shore power arrange-
ments and hardward items used in both ship and
shore installations, no specific installation in-
structions can be outlined in detail in this manual*
However, there are instructions and procedures
that should be followed before and during con-
nection to shore power. More detailed instruction
is usually provided by type commanders or your
own ships instruction.
Because of the dangers to personnel and equip-
ment, the connecting and disconnecting of shore
power should be under the direct supervision
FROM LIVE WIRE
1. DO NOT TOUCH VICTIM OR WIRE
2. DISCONNECT POWER IF POSSIBLE
3. USE DRY WOOD POLE OR DRY
ROPE TO REMOVE WIRE
4. RESUSCITATE IF NECESSARY
40,67(27D)
Figure 1-5. -Safety poster.
of the electrical officer s a qualified leading
electrician* and the shore activity personnel*.
All cables should be visually inspected for
any signs of defect* such as, cracks, bulges, or
indications of overheating. (Spliced cable is
extremely dangerous unless splices are properly
made.) Check the cables with a 500 V meggar
for insulation resistance between phases and
from each phase to ground.
Rope off the work area surrounding the ship's
shore power terminal box and tag with high-
voltage signs. With the ship's shore power breaker
tagged in the open position, test the terminals in
the terminal box to ensure they are deenergized.
With a 500 V meggar, test the insulation resistance
between the terminals and from each terminal
to ground.
Lay out the cable between the ship's terminal
box and the terminal box supplying power from
the shore activity, remembering to allow slack for
tides. Cables should not be permitted to rest on
sharp or ragged objects,, Excess cable should be
neatly faked out in a manner that will minimize
damage from vehicle and pedestrian movement.
Connect the cables to the ship's shore power
SHIPBOARD ELECTraCAL SYSTEMS
terminals according to the phase or polarity
markings in the box and on the cables.
With a voltmeter, check to ensure that the
supplying activity's shore terminals are de-
energized; then connect the cables to the shore
terminals.
Check for proper phase rotation by energizing
the shore power breaker from the supplying
activity. With proper phase rotation determined,
proceed with the transfer of electrical load to
shore power in accordance with Engineering
Department Operating Instructions.
After the cables are carrying the load, make
an inspection of the cable and connections to
detect any overheating.
When disconnecting shore power, observe the
same safety precautions outlined in the connecting
sequence except for meggering cables and check-
ing phase rotation. ENERGIZED SHORE POWER
CABLES SHOULD NOT BE MOVED,
IN USING CLEANING
SOLVENTS
Avoid using solvents for cleaning electrical
equipment as much as possible because of their
corrosive action, the possible injury to some
insulating materials, the risk of fire, and espe-
cially because of their toxicity.
If it is necessary to use a solvent, the
choice of solvent will depend on the instructions
on the solvent label, the fire risk involved, and
the facilities for maintaining adequate ventilation.
It might be beneficial to try a small amount on the
insulation to deter mine whether it will be injurious
to the insulation.
Inhibited methyl chloroform (1,1,1 trichloro-
ethane) is the solvent approved for use on elec-
trical equipment to remove grease and pasty
substances consisting of- oil and carbon or dirt.
This solvent is toxic and should be used with
care since concentrations of the vapor are
anesthetic and can be fatal. Dangerous concen-
trations of the vapor may cause irritation of
the eyes, dizziness, or disorientation. If any
of these symptoms occur, you will know imme-
diately that the amount of methyl chloroform
being breathed is dangerously high. Personnel
must secure the operation and evacuate the
space until proper ventilation is obtained. To
avoid misuse of this solvent, surface ships shall
stock only 1-quart containers.
Precautions with
Cleaning Solvents
During the use of any solvent the following
rules MUST be observed:
1. Guard carefully against fire.
2. Use explosion-proof portable lights if sup-
plementary lighting is required.
3. Have fire extinguishers available for im-
mediate use.
4. Prevent possible sparks caused by one
metallic object striking another.
5. If a spray or atomizer is used, ground the
nozzle.
6. Avoid saturation of the operator's clothing
with the solvent. Wear impervious (solvent re-
sistant) gloves to avoid contact with the skin.
Wear appropriate eye/face protective devices
when splash hazards exist (e.g. when pouring
solvent, etc.)
7. Provide adequate ventilation by means of
exhaust fans or other suitable means.
8. When inhibited methyl chloroform or tri-
chloroethane is being used, protection must
be provided against breathing the fumes, and the
operators should be under the observation of
someone familiar with artificial respiration.
9o Use of solvent in closed or very confined
spaces, where ventilation is lacking and for
some reason cannot be provided, requires that
fullface air supply respirators and related con-
trols be used. (Refer to damage control procedures
involving use of "buddy" system, lifelines, etc.).
10. Where normal (comfort) ventilation is
present and very small volumes of cleaning
solvent are used (few ounces, at most), the
minimum requirement is proper use of approved
organic vapor (charcoal) respirators. The pro-
cedure MUST be studied to minimize exposure
to the user, to adjacent spaces, and to nearby
personnel.
11. Where larger volumes of solvent are used
indoors, specially applied exhaust ventilation
and fullface air supply respirators, or equivalent
respiratory protection, are recommended.
12. When portable exhaust ventilation is ap-
plied, the exhaust face (exhaust end of the
flexible duct system) must be placed near the
operation for best capture of the "fumes." The
direction of ventilation should be checked to
Chapter 1 SAFETY
assure that fumes are being exhausted froin the
space and that the exhausted air is discharged
topside away from personnel and openings to
prevent recirculation of the fumes into other
occupied interior spaces.
13. Do not apply solvent to hot equipment or
use it in the presence of open flames.
14. Assure that solvents are properly labeled
according to hazards, that they are stored prop-
erly, and that adequate marking/labeling is
carried over into any subdivisions or transfer
of material into other containers.
IN MAINTENANCE AND
REPAIR WORK
When military considerations require that
electrical repair or maintenance work be per-
formed but prohibit deenergizing the circuits
involved, extreme measures of precaution must
be used. The work should be accomplished only
by adequately supervised personnel who are
fully cognizant of the dangers involved. Every
care should be taken to insulate the person
performing the work from ground and to use all
practical safety measures. The following pre-
cautions should be taken when applicable:
1. Provide ample illumination.
2. The person doing the work should not wear
wrist watch, rings, watch chain, metal articles,
or loose clothing which might make accidental
contact with live parts or which might accidentally
catch and throw some part of his body into contact
with live parts. Clothing and shoes should be as
dry as possible.
3. Insulate the worker from ground by means
of insulating material covering any adjacent
grounded metal with which he might come in
contact. Suitable insulating materials are dry
wood, rubber mats, dry canvas, dry phenolic
material, or even heavy dry paper in several
thicknesses, Be sure that any such insulating
material is dry, has no holes in it, and has no
conducting materials embedded in it. Cover
areas sufficiently to permit adequate latitude
for movement by the worker in doing the work.
4. Cover all metal, hand-held work tools with
an electrical insulating material. Taping method:
Cover the handle and as much of the shaft of the
tool as practical. Use two layers of rubber or vinyl
plastic tape, half lapped. Coating Method: Coat
tools with plastisol.
In an emergency, when time does not permit
application of the above materials, cover the tool
handles and tool shafts with cambric sleeving,
synthetic resin flexible tubing, or insulation tubing
removed from scraps of rubber electric cable.
5. Insofar as practical, provide insulating
barriers between the work to be done and any
live metal parts immediately adjacent to the
work.
6. Use only one hand to accomplish the work,
if practical.
7. Use a rubber glove on the hand not used
for handling tools. If the work being done permits,
wear rubber gloves on both hands.
8. Have men stationed by circuit breakers
or switches and have the telephone manned if
necessary, so that the circuit or switchboard
can be deenergized immediately in case of
emergency.
9. A man qualified in mouth-to-mouth resusci-
tation and cardiac massage for electric shock
should be immediately available while the work
is being done.
10. Energized switchboards are a great source
of danger. No work shall be undertaken on ener-
gized switchboards unless approval of the Com-
manding Officer has been obtained.
11. Be sure that the connections of removable
test leads on portable meters are tight. The
free end of an energized test lead which comes
adrift from its meter during a check of live
circuits is both a shock and a fire hazard.
WHILE WORKING ALOFT
At times, personnel are required to go aloft
for maintenance on running lights, to work on
wind direction and intensity equipment, etc.
Aside from the obvious hazard of falling from
the mast, certain other hazards exist: asphyxiation
from stack gases, electric shock, overexposure to
radiation from radar equipment, contact with
rotating or oscillating antennas, and overexposure
to inclement weather conditions.
Because of the numerous hazards, permission
to go aloft must be obtained from the Officer
of the Deck. Before granting permission, the OOD
shall ensure that all power to appropriate radio
and radar antennas is secured and that the con-
trols associated with the antenna are tagged
"Secured, Men Aloft." The OOD shall notify
ships tied alongside of his intent to send men
aloft and they will maintain the same safety
precautions. The OOD shall also notify the
Engineer Officer of the location of the men working
aloft so he can take the necessary precautions
to prevent such operations as lifting boiler
safety valves or blowing tubes or whistles.
SHIPBOARD ELECTRICAL SYSTEMS
Before sending any men aloft, the Officer in
Charge shall ensure that the men have read
and that they fully understand all the regulations
and safety precautions involved in going ploft.
Some of these regulations are listed below:
1. A man going aloft shall have the assistance
of another man.
2. Man working aloft shall wear a standard
Navy approved safety harness and safety lines
and shall use the saf-t-climb fall prevention
system ,
3 e Do not attempt to climb while loaded
with tools. Keep both hands free for climbing.
4. Ensure yourself of good footing and grasp
at all times.
5 9 All tools and equipment shall be secured
with preventer lines.
6. Have assistants stand clear and keep all
hands clear from below the working area.
7. Men going aloft shall wear tight clothing.
Loose or baggy clothing presents the hazard
of becoming caught or entangled.
8. When working on the stack, men shall be
particularly cautious to avoid dangerous gases
and fumes*
9. The Officer of the Deck shall be notified
immediately when work aloft has been completed.
NONSTANDARD
ALTERATIONS AND
EQUIPMENT
Many electrical hazards are introduced to the
ship by nonstandard equipment (personal equip-
ment) and nonstandard alterations (jury rigs).
Shipboard 115- volt, 60-'Hz lighting and receptacle
circuits are ungrounded,, In an ungrounded system
both conductors of the 115-volt system are above
ground potential and are a shock hazard. For this
reason use of personal electrical equipment,
which is normally designed to operate on 115-volt,
60-Hz grounded systems (the normal residential
power), is discouraged aboard ship. In much of
this equipment the chassis forms a part of the
circuit and the exposed metal parts are energized
thereby creating the danger of shock to personnel
who touch them. Moreover, grounding of these
metal parts to the ship's structure would place
a ground on the 115-volt system, jeopardizing
continuity of power. Personal equipment may be
permitted for use aboard ship if the following
conditions are met.
a. Adequate government-owned equipment is
not available to meet the need,
b. The equipment has been inspected by the
electrical/electronic shop and approved as safe*
Approved equipment shall be tagged and shall
indicate the interval between inspections. The
interval between inspections shall not exceed 6
months.
The approval criteria for personal equipment
can be found in NAVSHIPS' Technical Manual,
Chapter 300.
Jury rigs, such as bypassing overloads, over-
fusing circuits, rendering electrical interlocks
inoperative and any other unauthorized design
changes to equipment, are prohibited*
SAFETY INSPECTIONS
Conducting frequent informal safety inspec-
tions is one of the most effective methods to ensure
that precautions and accident prevention measures
are being adhered to. These inspections should be
used to identify and eliminate the various elec-
trical safety hazards and should be made on a
continuing basis.
Some of the more common discrepancies you
should look for on your tours are open covers
on fuse and power panels, meters not calibrated,
circuits over fused, improperly stowed equipment
near switchboards, workbenches not properly
insulated, and portable electric tools not safety
inspected in accordance with PMS.
Electrical safety posters of the type shown in
figure 1-6 are useful as safety reminders and in
promoting safety. Posters of this type should be
changed and rotated regularly to different working
areas so as to draw attention to them
8
Chapter 1 SAF ETY
ALL SHOOK UP?
I|GR<
EJ
GROUND IT BEFORE
IT GROUNDS YOU!
A GOOD THING
TO KEEP IN MIND
USING
PORTABLE ELECTRIC
Figure 1-6. Safety posters.
40.67(77C)
SHIPBOARD ELECTRICAL SYSTEMS
Figure 1-6, Safety posters continued.
4067(67B)
10
CHAPTER 2
POWER SUPPLIES
Ships of the U.S. Navy use electrical energy
for a variety of applications which range froin
simple lighting circuits to sophisticated and
complex weapons circuits and electronic circuits.
The electrical power is generated by power
supplies.
In this chapter we shall identify the different
types of power supplies, their basic operations,
their driving units and their regulation. We
shall give a basic explanation of how an elec-
trical voltage is generated. You will find more
detail in Basic Electricity, NAVEDTRA 10086-B.
Similarly, you will find simplified block diagrams
to describe functional operations of the closely
regulated power supplies that supply power to
certain weapons and other electronic systems on
modern ships. We will not attempt to show how
individual circuits function. You will find in-
formation on these circuits in Basic Electronics,
Vol. 1, NAVEDTRA 10087-C, NavShips
0967-000-0120, and individual manufacturer's
technical manuals.
VOLTAGE PRODUCED BY
MAGNETISM
Magnetic devices are used for thousands of
different jobs. One of the most useful and widely
employed applications of m agnets is the production
of vast quantities of electric power from mech-
anical sources. The mechanical power may be
provided by a number of different sources, such
as gasoline or diesel engines and water or
steam turbines. However, the final conversion
of these energy sources to electricity is done
by generators which use the principle of electro-
magnetic induction. We shall discuss the funda-
mental operating principle of ALL such
electromagnetic-induction generators.
To begin, there are three fundamental con-
ditions which must exist before a voltage can be
produced by magnetism:
1. There must be a CONDUCTOR in which
the voltage will be produced.
2 There must be a MAGNETIC FIELD to
cut the conductor,,
3 There must be RELATIVE MOTION between
the field and the conductor. Either the conductor
must be moved to cut across the magnetic lines
of force, or the field must be moved to cut
across the conductor.
In accordance with these conditions, when a
conductor or conductors move across a .magnetic
field so that the lines of force are cut, electrons
WITHIN THE CONDUCTOR are impelled in one
direction or another. Thus, an electromotive force
(emf) or voltage, is produced.
In figure 2-1, note the presence of the three
conditions needed to create an induced voltage:
1. A magnetic field exists between the poles
of the C- shaped magnet.
2. There is a conductor (copper wire).
3 There is relative motion. The wire is moved
back and forth across the magnetic field.
In figure 2-1A, the conductor is moving toward
the front of the magnet (note the direction of
motion) because of the mechanical force The
right-hand end becomes negative, and the left-hand
end becomes positive* The conductor is stopped
in figure 2-1B. Motion in aliinnated (one of the
three required conditions), and there is no longer
an induced emf. Consequently, there is no longer
any difference in potential between the two ends
of the wire. The conductor in figure 2-1 C is
moving away from the front of the magnet (motion
reversed). An induced emf is again created.
However, note carefully that the reversal of
motion has caused a reversal of direction in
the induced emf.
If a path for electron flow is provided between
the ends of the conductor, electrons will leave
the negative end and flow to the positive end.
As shown in figure 2-1D. Electron flow will
continue as long as the emf exists. In studying
figure 2-1, please note that the induced emf
11
SHIPBOARD ELECTRICAL SYSTEMS
MAGNET
MAGNETIC
COPPER WIRE
CONDUCTOR
DIRECTION
OF MOTION
EMF
NO
MOTION
INDUCED EMF
REVERSED
(C)
MOTION
REVERSED
Figure 2-1 Q Voltage produced by magnetism a
236.24
could also have been created if the conductor
were held stationary and if the magnetic field
were moved back and forth.
This basic principle will be used as we discuss
the types of generators in this chapter*
DIRECT CURRENT
GENERATORS
Various auxiliaries, amphibious and mine
warfare ships, patrol landing and service craft,
utilize d.c, generators as the main source of
electrical power . A d.c a generator is a rotating
machine which converts mechanical energy to
electrical energy. Figure 2-2 shows an open-
ended d.c. generator. A d.c. generator consists
essentially of the following components:
1. A steel frame or yoke containing the
magnetic pole pieces and field windings.
2. An armature consisting of a group of
copper conductors, mounted in a slotted cylin-
drical core, made up of thin steel disks called
laminations,
3 W A commutator to cause the current to flow
in one direction through the external circuit
4o Brushes with brush holders to carry the
current from the commutator to the external
load circuit.,
^ The d,c. generator must rotate at designed
sfpeed to produce the designed voltage Thus
any device that will cause generator rotation
is commonly called a prime mover. One of the
most common prime movers for d a c. generators
is the diesel engine. Figure 2-3 shows a diesel-
driven d c. generator 9
The d.c, generator normally used on naval
vessels is of stabilized shunt construction, which
has inherently good voltage regulation. Basically,
voltage regulation is the ability of a generator
12
Chapter 2 POWER SUPPLIES
FIELD POLE
a
FIELD CORE
YOKE
BRUSHES
COMMUTATOR
ARMATURE
Figure 2-2. Open- Ended d.c. generator.
236.328(A)
;o maintain a constant output (terminal) voltage
mder varying loads. If closer regulation is
squired, a voltage regulator will be utilized.
A voltage regulator consists of a sensing
levice and a mechanical or electrical control
slement to produce changes in the generator
leld current which are necessary to maintain a
>redetermined constant generator terminal
roltage.
ALTERNATING CURRENT
GENERATORS
Alternating current generators, normally re-
erred to as alternators, are used as the main
source of electrical power on all combatant,
ind many other types of Navy ships. With very
ew exceptions these alternators are 450-volt,
J-phase, 60-hertz machines.
The alternators (a.c,) are smaller in size
and have less weight that d.c. generators Main-
tenance requirements are also reduced with a a c.
CONSTRUCTION OF
ALTERNATORS
Alternators are usually of the d.c. excited
rsvolving field type However, small alternators
(25 kW and below) may be of the revolving
armature type. Salient pole type rotors, which
produce a rotating field, are used on alternators
of 1800 rpm and below. (See figure ^2-4B.)
An amortiseur (damping) winding is provided
on salient pole rotors to dampen hunting effects
when generators are operated in parallel and to
equalize flux distribution when an unbalanced
load condition exists. These windings are similar
to a squirrel-cage and are placed near the pole
face of each field pole.
13
SHIPBOARD ELECTRICAL SYSTEMS
Figure 2-3. Diesel-driven d.c. generator.
77.70
The cylindrical rotor (fig. 2-5E) is a solid
steel forging. Slots in which the fxeld coils a^t
^bedded are milled into the forging. T^secoUs
are usually arranged to form either two or four
magnetic poles. The diameter of the rotor
'
*"***' ** vAa-gv^o W 1 LI1 el biD aJLl
, ""' 7^ r t0r Iength is extended to obtain
the required field strength.
TYPES OF DRIVE
Shipboard alternators are driven by steam
turbines, diesel engines, or electric motors
(Gas turbines are used in many of the newer
installations.) The steam turbines norm ally ooer-
ate at 12,000 rpm and drive the alternators
through reduction gears. Turbine driven 400-Hz
alternators, however, are usually directly con-
nected to the turbine.
14
Engine-driven alternators are usually of the
sahen pole type. The 60-H Z alternators are
Erectly connected, while the 400-Hz installations
are usually driven through step-up gears.
r " dri H n altern ators are used to convert
current to alternating current, or alterna-
ting current of one frequency to alternating
current of a different frequency "wrnanng
60-HERTZ ALTERNATORS
alternator shown in fig.
*in Shlp ' s ^^vice alternators found
aboard certain frigates. The alternator is rated
Chapter 2 POWER SUPPLIES
A. STATOR
B. ROTOR
139.43X
Figure 2-4. Low- speed salient pole engine-driven
alter nator
at 450 volts and produces 750 kW, 3~phase, 60-Hz
power at 1 200 rpm . The totally enclosed alternator
(fig. 2-7) has a double-tube type air cooler located
on top of the alternator stator. The stator (fig.
2-8) has six temperature detectors embedded
in the slots of the stator to monitor stator
temperature during operation. Space heaters are
located inside the stator on the lower part of
the frame. These heaters prevent condensation
of moisture on the windings during shutdown
periods.
The alternator rotor (fig. 2-9) is of the
salient pole type. It has six poles and two
bronze collector rings to apply the d.c. power
(revolving d.c. field). As the turbine drives the
rotor, the magnetic field of the rotor cuts the
coils of the stator to produce a voltage in the
stator. The electrical load is connected to the
stator.
400-HZ GENERATOR
In modern-day electronics and computers,
the need arose for miniaturization of equipment
ROTOR
139.44X
Figure 2-5. High-speed turbine-driven
alternator .
in both aircraft and naval vessels. Experi-
mentation with various frequencies showed that
a 400-Hz system would meet these require-
ments. A higher frequency will produce a higher
speed, as well as a higher torque, for a given
size motor. Therefore, a smaller size 400-Hz
motor can be used without affecting the output.
Experimental efforts proved that the 400-Hz
system was unsatisfactory as the sole source
of power for shipboard use. "This system was
found to be impractical for large power appli-
cations because of heat dissipation and voltage
losses. The 400-Hz system is used in equipment
that requires the higher frequencies and wherever
the smaller motors are advantageous. The 400-Hz
power supplies furnish power for systems such
as the gyrocompass, radar, sonar, andfire control
circuits. Since 400-Hz power is generated in the
same manner as 60-Hz power, no attempt will
be made to discuss the generation of 400-Hz*
15
SHIPBOARD ELECTRICAL SYSTEMS
AC GENERATOR
i
REDUCTION
GEAR
TURBINE
27.356X
Figure 2-6. Turbine-Generator (alternator) set*
A typical example of a 400-Hz system aboard
ship is a 30-kW motor-generator set,
30-kW MOTOR GENERATOR SET
A typical closely regulated motor-generator
set (fig 2-10), consists of a 450- volt, 3-phase,
60-Hz, 50-hp, wound rotor induction motor which
drives a 450-volt, 3-phase, 400-Hz, 30-kW gener-
ator* The set is regulated and controlled by a
voltage and frequency regulating system which
is housed in the rotor resistor and regulator
unit control cabinets and by a magnetic controller
with associated pushbuttons and switches which
are located in the control cabinet (fig. 2-10).
The magnetic controller is a conventional
across-the-line semiautomatic motor controller
(starter). The voltage regulating system supplies
the proper field current to the generator to
maintain the generator output voltage to within
1/2 of 1% of the rated output voltage for all
load conditions. The frequency regulating system
controls the speed of the drive motor to maintain
the output frequency of the generator to within 1/2
of 1% of its rated value for all load conditions. In
addition, power sensing networks are included to
eliminate speed droop with increased generator
loads and to maintain equal sharing of the load
between paralleled generators.
VOLTAGE REGULATORS
As previously described most d.c. generators
have inherently good voltage regulation character-
istics. Due to a.c tt characteristics alternators
have poor voltage regulation,, To compensate for
this disadvantage, a voltage regulator must be
incorporated* There are several types of voltage
regulators used in naval vessels (1) indirect
acting rheostatic, (2) direct acting rheostatic,
(3) rotary amplifier, and (4) combined static
excitation and voltage regulation system all
use the same basic principles. Voltage regulation
is accomplished by controlling the amount of
current in the generator field* In this chapter
we shall give a basic description of the combined
16
Chapter 2 POWER SUPPLIES
POLE
COOLER
!39o44X
Figure 2-7. Turbine - Driven alternator
(cooler shown).
HEATERS
Figure 2-8. Stator.
27.85X
COLLECTOR
RINGS
Figure 2-9 Salient pole rotor.
27o86X
static excitation and voltage regulation system
which is being used on most new construction
ship So
COMBINED STATIC
EXCITER AND VOLTAGE
REGULATION SYSTEM
The combined static ex dter and voltage regu-
lation system consists of a (1) static exciter,
(2) field flashing circuit, (3) automatic voltage
regulator, and (4) manual voltage control.
Static Exciter
The static exciter, fig. 2-11 consists of a
3-phase, bridge rectifier (CR1), three linear
reactors (LI, L2, L3), and three saturable
current potential transformers (SCPT) (Tl, T2,
T3). Each SCPT has a current winding, a poten-
tial winding, a secondary winding, and a control
winding. These are connected in a 3-phase
circuit, with the output of the secondary windings
rectified and applied to the generator field.
At no load, the input to the SCPT's is from
the generator terminal voltage, through the poten-
tial windings and linear reactors.
Under load, the line current flowing through
the current windings adds a component that is
approximately proportional, in magnitude and
phase angle, to the voltage in the generator.
The control winding current changes the
output of the SCPT by saturating the cores.
17
SHIPBOARD ELECTRICAL SYSTEMS
ROTOR RESISTOR
CABINET-
CONTROL
CABINET-
REGULATOR UNIT
CONTROL CABINET-
I
r >~ , if .-v*' isi
MOTOR GENERATOR
40.111
Figure 2-10. Motor generator set with control equipment.
Field Flashing Circuit
Since the static exciter cannot supply field
current until the generator voltage is built-up,
the field flashing circuit provides for the initial
voltage buildup. As part of the circuit, a small
permanent-magnet alternator (PMA), which is
driven by the prime mover, furnishes excitation
current through rectifier CR 5 (fig. 2-12).
As the generator starts to turn over, the
PMA builds up an a.c. output which is rectified
by the 3-phase full- wave-bridge rectifier CR5
and furnishes d.c. to excite the generator field,
thus building up a generator voltage.
Automatic Voltage Regulation
The static exciter will not supply the exact
amount of field current required to maintain
constant generator terminal voltage under all
operating conditions because of:
1 . The effects of a.c. generator field saturation
2. Changes in field resistance because of heat
3. Changes in ambient temperature
4. Normal manufacturing tolerances
Therefore, the direct-current supply to the
control windings of the SCPT's is controlled by
an automatic voltage regulator so that the gener-
ator terminal voltage is held nearly constant.
For explanation purposes the automatic voltage
regulation system is subdivided as follows:
1. Sensing circuit
2. Reference circuit
3 Comparison circuit
4. Magnetic amplifier circuit
5. Stabilizing circuit
SENSING CIRCUIT. To obtain the best regu-
lation during unbalanced load conditions, a sensing
circuit (fig. 2-13) responds to the approximate
average value of the three line voltages. This
circuit consists of a 3-phase potential trans-
former (T4), a rectifier (CR4), a reactor (L4),
and a capacitor (Cl).
Transformer T4 reduces the line voltage to a
convenient value and rectifier CR4 converts the
3-phase a.c. voltage to a d.c. voltage. If an
18
Chapter 2 POWER SUPPLIES
r--~n
i j^ |
I PFN V
i r~ T !ri
lit i
CURRENT WINDINGS i
i '
r~
I
"F 3 ~"|
FIELD
RI8
H3-
CRI
k M ift Ml i
i
I 1 1
u . .' 1
i
r" L ~~"i
1 1 I
i
_| /Y L2^|
I i
I POTENTIAL WIN
DINGS
1
1
1
1
1
1
1
, ' /
ywvx.
vvv-%_.
J /"VVVN 1
L J
W T w
1 \ '
! ! ~~ !
D
I
yn m Li
SECONDARY WINDINGS 1
1 1 1
M|M
FIELD
RECTIFIERS
II 1 "
jOIhj! j[HSh|J
|H
WYxX.
TO *
ITOMATIC
OLTAGE
GULATOR
<;
1 CONTROL WINDINGS ' "
1 ' II
i 1 i J L_
TO
LOAD
Figure 2-11, Static exciter circuit.
11.30
unbalanced load condition causes the three line
voltages to become unequal, the d.c. output
of CR4 will have considerable ripple. Reactor
L4 and capacitor Cl comprise a filter network
which averages the varying d.c. output of CR4
so that the voltage across Cl is essentially
constant and is approximately the average of the
three line voltages,
REFERENCE CIRCUIT. The reference am-
plifier (fig, 2-14) supplies a nearly constant
reference voltage to the emitter of Ql in the
comparison circuit.
Rectifier CR2 consists of a zener diode,
which is a rectifier that operates in the break-
down (or zener) region and has a nearly constant
11. 7- volt drop for a large variation in current.
If the voltage applied to R5 and CR2 increases,
the current increases, and the increase in voltage
is absorbed as IR voltage drop across R5. The
voltage across CR2 remains almost constant
because of its flat voltage characteristic.
COMPARISON CIRCUIT, The comparison
circuit (fig. 2-14) compares the sensed voltage
SHIPBOARD ELECTRICAL SYSTEMS
/
\ ,
Ml iy
Mm M i
' I
V
Win iy i
CR5
(F2) (Fl)
HMHBMHIBK . . * MHMMMMHI
GENERATOR
FIELD
Figure 2-12. Field flashing circuit.
11.30
with the reference voltage by means of transistor
Ql and acts on the magnetic amplifier to correct
any difference.
Resistors Rl, R2 (automatic voltage- control
resistor) and R3 form a voltage divider. The
voltage between the slider of resistor R2 (sensed
voltage) and the negative side of CR4 is always
proportional to the output of CR4 and to the
average line voltage.
SOURCE
SIGNALyC!
This sensed voltage is applied to the base
of transistor Ql and the reference voltage is
applied to the emitter. Whenever the sensed
voltage is high, transistor Ql will be biased
(turned) on, causing collector to emitter current
to flow through magnetic amplifier control winding
F2-F4, thereby phasing the magnetic amplifier
on (saturating the core) which increases the
gate winding current (A1-A2; B1-B2) in the
magnetic amplifier.
If the generator output voltage is low, the
sensed voltage will be low, transistor Ql will
be biased (turned) off, and no control current
will flow in the control winding F2-F4 of the
magnetic amplifier, which will operate in an
unsaturated condition. This, in turn will raise
output voltage.
Voltage is adjusted by changing the position
of the slider on the automatic voltage-control
resistor R2. If the slider is turned toward
11.30
Figure 2-13. Sensing circuit.
resistor R3, a smaller portion of CR4 output
voltage is compared to the reference voltage,
and the regulator acts to increase the line
voltage as well as the voltage at the slider
until the balance is restored. The line voltage
is lowered by turning the slider toward resistor
Rl.
MAGNETIC AMPLIFIER CIRCUIT. Changes
in the generator voltage produce changes in the
current in the comparison circuit in the order
of milliamperes. However, it is desirable to have
these small current changes produce changes in
the order of amperes in the control windings
of the SCPT's. This is accomplished by using
a magnetic amplifier (fig. 2-14) between the
comparison circuit and the control windings
of the SCPT's.
20
Chapter 2 POWER SUPPLIES
TO EXCITER
CONTROL WINDING
FILTERED
OUTPUT
OF CR4
MAGNETIC
AMPLIFIER
COMPARISON
CIRCUIT
SENSED
VOLTAGE
REF.
CKT.
Figure 2-14. Reference/Sensed Voltage /Comparison Circuit.
11.30
STABILIZING CIRCUIT. In any closed-loop
regulating system containing more than two
prevent this condition, a stabilizing circuit has
been inserted between the field of the generator
significant time constants and having relatively or exciter output and the comparison circuit.
high gain, there can be a condition of sustained
The elementary diagram for this stabilizing
oscillations, sometimes called "hunting,," To circuit is shown in fig 2-15. Resistor Rll and
C3A
RI2B hHRI3A RI3B
11.30
Figure 2-15. Stabilizing circuit.
21
SHIPBOARD ELECTRICAL SYSTEMS
capacitor C2 form a filter to remove the normal
ripple from the exciter output voltage. Resistors
R12 and R13 and capacitors C3 provide optimum
system stability.
Manual Voltage Control
The generator output voltage can be controlled
manually by manual voltage control rheostat
R20 (fig. 2-16).
Rectifier CR1 voltage (exciter output voltage)
is applied to the SCPT control windings through
manual control rheostat R20. An increase in
R20 resistance decreases SCPT control current,
which increases the exciter output voltage .
SPEED REGULATION
Speed regulation of the prime mover is needed
on both a.c. and d.c. generators,. As load is
applied to the generators, the prime movers
tend to slow, thus changing the characteristics
of the generator output. Although the Navy uses
many types of speed regulators, we shall discuss
only the newer type which is being installed
on newly constructed vessels.
ELECTROHYDRAULIC
LOAD-SENSING SPEED
GOVERNOR
Electrohydraulic load- sensing speed gover-
nors are used with ship's service generators
in electrical systems which require closer fre
quency regulation than that provided by mechanics
type governors. Electrohydraulic governors hav
met with great success on both steam-turbim
and diesel-driven generators.
An electrohydraulic governor may be operate
as an isochronous governor (constant speed at a]
loads) or with speed droop which permits par-
alleling with other generators that have conven-
tional fly- weight governors.
Operation
The steam valve or throttle that controls thi
prime mover fuel supply is operated by ai
electrohydraulic actuator which responds to th<
output of a magnetic amplifier. Generator speet
and load signals are fed into the transistor ampli-
fier to produce a power output sufficient to
operate the electrohydraulic actuator which cor*
rectly positions the steam valve or throttle
The speed signal is usually provided by i
small permanent magnet generator driven fron
the shaft of the prime mover or ship's service
generator. The speed signal is sometimes ob-
tained by sensing the output frequency of the
ship's service generator, but the loss of signal
in case of short circuit on the generator is
disadvantage of this method. The speed signal
is applied to a frequency sensitive circuit and
to a reference circuit in the governor control
unit. The output of this circuit is an erroi
TO SCPT
SECONDARY WINDINGS
GENERATOR
FIELD
CRI
TO CONTROL
WINDINGS
ON SCPT
R20
MANUAL
Figure 2-16. Manual voltage control circuit.
22
11.30
Chapter 9 POWER SUPPLIES
signal if there is any deviation from rated speed.
The error signal is applied to the transistor ampli-
fier and acts to restore rated speedo Stability
is obtained by the use of electrical feedback
circuits.
Load-measuring circuits are used in the
electrohydraulic governor to obtain proper load
ratio on each paralleled generator. Most governing
systems are so designed that any change in
load produces a signal which is fed into the
transistor amplifier and acts to offset any antici-
pated speed change due to load change. The
load-measuring circuits on governors of all
generators that operate in parallel are connected
by a tie cable. The governor may be designed
or preset so that each paralleled generator
will equally share the total load, or a load ratio
adjustment may be provided. Any deviation in
proper load ratio produces a circulating current
in the tie cable. The circulating current acts in
the transistor amplifier circuit to increase or
decrease fuel supplied to the generator prime
movers until proper load ratio is achieved.
The electrohydraulic load-sensing governor
used in this discussion is made up of four
major units (fig. 2-17) the EO-M control box,
the load signal box, the EG-R hydraulic actuator,
and the valve operator.
The input signal (voltage) is proportional
to the speed of the permanent magnet generator
(PMG) and is applied to the EG-M control box
(fig. 2-18). The control box compares this voltage
with a reference voltage and, if there is a
difference, supplies an output voltage to energize
the EG-R hydraulic actuator. A pilot valve
plunger in the actuator directs oil to or from
a remote servo in the valve operator. The
valve operator moves the mechanism to increase
or decrease the steam, which returns the turbine
speed to normaL
The load signal box detects changes in load
before they appear as speed changes and applies
a proportional voltage to the EG-M control box.
The load signal box detects these changes through
the resistor box, which develops a voltage from
the secondary of current transformers* This
voltage is compared with the generator load
output voltage and, if a difference exists, the
load signal box applies a proportional voltage to
the control box.
The droop switch allows parallel operation
with governors of types other than EG. The
circuit breaker auxiliary contact provides a path
for control load signals to other paralleled units.
NO-BREAK POWER
SUPPLY SYSTEM
A no-break power supply system provides an
uninterrupted electrical power supply which is
relatively constant in voltage and frequency
under all load conditions. The no-break power
supply automatically takes over when the normal
power supply is interrupted, off-frequency, or
off- voltage o The no-break power supply system is
presently being used by ships using the Central
Operations Systems and by ships with equipment,
control, or computer systems which need an
uninterrupted electrical power supply for effective
operation.
The system uses a motor-generator set,
batteries, and associated controls to provide
its regulated output. Either unit of the motor-
generator set can perform as a motor with the
other as generator, thus permitting two modes
of operation.
MOTOR GENERATOR
MODE 1
In mode 1 operation of the motor-generator
set (fig. 2-19A), the a.c. end of the set is driven
from the ship's service power supply; the d.c.
end is a generator providing power to the system
batteries. This mode of the motor-generator
operation exists when the ship's service power
supply is meeting the voltage and frequency
requirements of the critical load.
MOTOR-GENERATOR
MODE 2
Mode 2 operation of the motor-generator
set (fig. 2-19B) represents the condition by
which the set receives power from the batteries,
and the a.c. end of the set provides the power re-
quirements for the critical load. Mode 2 is
referred to as the Stop Gap Operation.
STATIC POWER SUPPLIES
Static power supplies using solid-state com-
ponents are being used for many shipboard
23
SHIPBOARD ELECTRICAL SYSTEMS
WSS538SSD
EG-M CONTROL
BOX
LOAD SIGNAL
BOX
EG~R
ACTUATOR
VALVE
OPERATOR
111.150X
Figure 2-17. Electrohydraulic load- sensing governor system components,,
applications, specifically, 400-Hz equipment. We
have already described an MG set which con verts
60-Hz to 400-Hz. Static power supplies offer
certain advantages over MG sets, such as lighter
weight, smaller space requirements, and no
moving parts, hence quieter operation, less
maintenance, higher efficiency, and faster reac-
tion time to transient disturbances. Static power
supplies can be designed to change d.c. to a.c.
a a c. to d c., or a.c. to a.c, of different frequencies.
5 kW 250 VDC, 120
VAC 400 Hz STATIC
INVERTER
The model 4345D Static Inverter (fig. 2-20)
develops a closely regulated source of 400-Hz,
24
Chapter 2 POWER SUPPLIES
REMOTE SERVO
(VALVE
OPERATOR)
DROOP
SWITCH
RESISTOR
BOX
CIRCUIT BREAKER
AUXILIARY CONTACT
PARALLELING
LINE
TO OTHER UNITS
SPEED SETTING
POTENTIOMETER
CRITICAL
LOAD
450 VAC
3-PHASE
60 HERTZ
SHIP 450 VAC
DmA/FD 3 HAot '
rUWtK cr\ WFRT7
SUPPLY -
< i
DP
r*
n
(AC
MOTOR
^ DC
GENERATOR
BATTERIES
MOTOR- GENERATOR SET
A MODE \ NORMAL OPERATION FROM THE NORMAL SUPPLY
111.151
Figure 2-1 8 Block diagram of the electrohydraulic load-sensing governor system.
3-phase power from a 240 VDC source. We
shall not attempt to cover the circuitry of this
system in our discussion. One basic circuit will
be used as an example of how the theory is
possible.
Basically, d.c. power is converted to a.c.
power in the inverter sections by a rapid change
in the direction of current flow through a trans-
former. In figure 2- 21 A the main d.c. source
is placed across the primary of a transformer.
If switch SI is closed, a voltage is produced on
the secondary of transformer Tl. When SI
is reopened, the voltage decreases to zero.
A similar action occurs if S2 is closed and
reopened, but the voltage produced is of opposite
polarity. Referring to figure 2-21B a square
wave form would be produced. By timing the
switching action and adding a filter (fig. 2-21C)
to the secondary of Tl you can obtain a 400-Hz
sine wave (fig. 2-21D). In the inverter, SI and S2
are replaced by semiconductor devices. There are
two inverters which operate 90 out of phase
to produce a standard two-phase power. The 2-
phase, sine- wave power is then converted to
3-phase power by a SCOTT T-connected Trans-
former. Detailed functions and test points should
CRITICAL
LOAD
450 VAC
3-PHASE
60 HERTZ
SHIP ^gQ VAQ
SLRVICt -a PUAOC _
DOWPQ O-KMAbt
rUWtn cr > UPDTT
SUPPLY 60 HtRTZ .
i
, i
r~
4-
~|
AC DC
GENERATOR | MOTOR
BATTERIES
MOTOR-GENERATOR SET
B MODE 2 STOP GAP OPERATION FROM ASSOCIATED BATTERIES
Figure 2-19. Block diagram of
power supply.
the
77.297
no-break
25
SHIPBOARD ELECTRICAL SYSTEMS
OUTFIT
V
L
A
G
SI CLOSED S'
n
1 OPENED
TIME
S1
OUTPUT
40.79X
Figure 2-20. Static inverter,,
be obtained from the manufacturers technical
manual.
150 kW 440 VAC 60-Hz,
450 VAC 400-Hz STATIC
CONVERTER
Some newer ships are using a centralized
400-Hz power supply to meet the ever-increasing
400-Hz equipment demands. The newer DD's use
a static power converter that produces an output
of 450 VAC, 400 Hz, 3 phase at a maximum of
150 kW continuous power , An input of 440 VAC,
60-Hz, 3 phase is required (fig. 2-22) .
TIME
27.316
Figure 2-21. Basic inverter.
26
Chapter 2 POWER SUPPLIES
Teledyne Inet 187.5 KVA, 150 KW, 60 Hz to 400 Hz Power Converter
Figure 2-22. Power converter assembly.
27.315X
The 150 kW converter works basically the
same as the 5 kW model 4345D inverter, first
changing the a.c. to d.c., then using the same
basic switching action as the 5 kW inverter
Note in figure 2-23 that the 440 VAC 60 Hz
goes into the 60 Hz to DC CONVERSION FUNC-
TION. This section converts the a.c. to approxi-
mately 390 VDC. The LOW VOLTAGE POWER
27
DISTRIBUTION section provides low voltage
power from the 440 VAC input to operate tran-
sistors, logic circuits, and other integrated cir-
cuits in the rest of the converter. The CONTROL
FUNCTION provides signals that control the
operation of the converter. Signals from other
functions are processed to provide output voltage
control signals and, in the event of faults,
SHIPBOARD ELECTRICAL SYSTEMS
I" 8&* <sa-
CO CO CO
10
t: G z o
s s
PROTECTION 1
BYPASS
_ U.
fe
rl
fi
g
o
h
0)
I
Pk
d
&
8
T(
I
D4
s
55
28
Chapter 2 POWER SUPPLIES
TERMINAL
BOARD
CABINET
ASSEMBLY
CHASSIS
ASSEMBLY
HEAT SHIELD
(SHOWN REMOVED)
DOOR
ASSEMBLY
CIRCUIT
CARD
ASSEMBLY
Figure 2-24, Line voltage regulator type 1ES25007 front views open and closed.
111.102
SHIPBOARD ELECTRICAL SYSTEMS
SECONDARY
INPUT
o
T!
PRIMARY
T2
POWER
THYRISTOR
PULSE
AMPLIFIER
OUTPUT
o
ZENER
REFERENCE
CIRCUIT
SYNCHRONIZED
PULSE
GENERATION
t
ERROR
SIGNAL
AMPLIFIER
111.102
Figure 2-25. Line voltage regulator simplified
block diagram.
to provide signals that automatically shut down
the converter. The REFERENCE 400-HZ DE-
VELOPMENT FUNCTION generates signals to
drive the DC 400-HZ CONVERSION FUNCTION
circuits. These signals are developed by a
4800-Hz oscillator (pulse generator) whose fre-
quency is controlled by a d.c. input. The DC
TO 400-HZ CONVERSION FUNCTION contains
the switching devices necessary to convert the
d.c. to 400 Hz a.c. The frequency output is
controlled by signals from the REFERENCE
400-HZ DEVELOPMENT FUNCTION, and the
voltage output is controlled by signals from the
CONTROL FUNCTION. Because of the relatively
high power output, a heat exchanger is incorpo-
rated to provide cooling to the inductors, trans-
formers, and rectifiers for each of the three
phases. A continuous flow of seawater cools a
closed fresh water system. The fresh water is
circulated by a pump through the heat exchanger,
LINE VOLTAGE REGULATORS
Line voltage regulators are used on naval
ships for equipment that requires closely regu-
lated voltage under varying load conditions,
There are several designs of line voltage
regulators available. The basic operation de-
scribed in the next section will cover a typical
design.
TYPE 1ES25007 LINE
VOLTAGE REGULATOR
The type 1ES25007 line voltage regulator
(fig. 2-24) will maintain 114 V, 75 amp, 87
kVA at 0.5%. Regulation is achieved by con-
trolling a transformer directly in line with the
load. The operation is designed around Thyris-
tors, which control the primary of T-l. Thyris-
tors are transistors which have a switching
characteristic.
A line voltage is sensed at transformer T-2
(fig. 2-25) and compared with a zener diode
network. Any error is then amplified and sent
to the synchronized pulse generator which is
designed to keep the error signal in phase with
line voltage. The error signal then goes through
a pulse amplifier which fires (switches) the
Thyristors to either aid or buck the voltage
at Transformer T-l. If sensed line voltage
is suddenly increased, a buck signal is applied
to T-l, tending to oppose this increase. If a
reduction in line voltage occurs, an opposite
action will take place
30
CHAPTER 3
DISTRIBUTION SYSTEMS
Chapter 2 dealt with different methods of
snerating voltage using various types of equip-
tent. In this chapter we shall discuss how this
Dwer (generated voltage) is distributed on naval
assels and how selective tripping is utilized.
/e shall also discuss the devices used toaccom-
Lish power distribution in a safe, reliable
ad efficient manner.
The a.c. power distribution system aboard
lip consists of the a.c. power plant, the means
> distribute the power, and the equipment which
snsumes the power, such as lighting systems
ad electric motors. The power plant is either
le ship's service electric plant or the emergency
lectric plant. The means of distributing the
lip's service power is through load centers
ad power panels.
SHIP'S SERVICE POWER
DISTRIBUTION
Most a.c. power distribution systems in naval
3ssels are 450-volt, 3-phase, 60-hertz, 3-wire,
agrounded systems.
The ship's service generator and distribution
(vitchboards (fig. 3-1) are interconnected by
as ties so that any switchboard can be connected
> feed power from its generators to one or
tore of the other switchboards. The bus ties
Iso connect two or more switchboards so that
le generator plants can be operated in parallel,
he power distribution to loads can be from
le generator and distribution switchboards or
om switchgear groups to load centers, to
Istribution panels, and to the loads, or directly
*om the load centers to larger loads.
EMERGENCY POWER
DISTRIBUTION
The emergency power distribution system
ipplies an immediate and automatic source of
electric power to a limited number of selected
vital loads in the event of failure of the ship's
service distribution system. This system, which
is separate and distinct from the ship's service
distribution system, includes one or more emer-
gency distribution generators and switchboards.
Each emergency switchboard (fig. 3-2) is supplied
by its associated emergency generator. The
emergency feeders run from the emergency
switchboards and terminate in manual or auto-
matic bus transfer equipment at the distribution
panels or at loads for which emergency power is
required. The emergency power distribution sys-
tem is 450-volts, 3-phase, 60-hertz with trans-
former banks at the emergency distribution
switchboards to provide 120-volt, 3-phase power
for the emergency lighting system.
The emergency generators and switchboards
are located separately from the ship's service
generators and distribution switchboards. The
emergency feeders are located near the center-
line and higher in the ship (above the waterline)
than the normal and alternate ship's service
feeders. This arrangement provides horizontal
separation between the normal and alternate
ship's service feeders and vertical separation
between these feeders and the emergency feeders,
thereby minimizing the possibility of damaging
all three types of feeders simultaneously.
The emergency switchboard is connected by
feeders to at least one and usually to two
different ship's service switchboards (fig 3-3).
One of these ship's service switchboards is the
normal source of ship's service power for the
emergency switchboard and the other is the
alternate source. The emergency switchboard and
distribution system is normally energized from
the normal, or preferred source of ship's service
power. If this source of power should fail, bus
transfer equipment automatically transfers the
emergency switchboard to the alternate source
of the ship's service power. If both the normal
31
SHIPBOARD ELECTRICAL SYSTEMS
X
CO
CD
CD
O
CD
CO
CO
0>
3,
32
Chapter 3 DISTRIBUTION SYSTEMS
77.166X
Figure 3-2. Emergency switchboard.
and alternate source of ship's service power
fails, the emergency generator will start auto-
matically within 10 seconds after power failure
and the emergency switchboard will automatically
transfer to the emergency generator.
CASUALTY POWER
DISTRIBUTION SYSTEM
Damage to ship's service and emergency
distribution systems during wartime led to the
development of the casualty power system. The
casualty power distribution system provides for
making temporary connections (runs) to vital
circuits and equipment (fig. 3-4). The system
is limited to only those facilities necessary
to keep the ship afloat and to permit the ship
to get out of the danger area. The system also
supplies a limited amount of power to armament,
such as antiaircraft guns and their directors
to protect the ship when in a damaged condition.
Optimum continuity of service is ensured
in ships provided with ship's service, emergency,
SHIPBOARD ELECTRICAL SYSTEMS
;So
r
i\
1 !
1
ri i
1
T i '
1 .
> ' L^
1 <
1
} 1
1
1 1
Ico^
1
1
1
lo
CD
O
lUJ
T
CJ
in
,co
/"""N A _->/
! UJ *
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^A
Iw
IQ.
fl
i
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li
h
CD
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CM
<UJ
tf)
|CO
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ILJ
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1
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IQ:
i
,UJ
Ico
IO
,QL *
,x
to
1 (
1
I
>!
_j f-
l
l /-
Z*7
en
a:
(T
CD
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QC
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O
o
cc
UJ
O
Q
oj
a
o
S
1
H
4->
<D
O
O
JH
-->
QQ
r-4
*a
CO
CO
O DO
2(7) h-
34
Chapter 3 DISTRIBUTION SYSTEMS
FRAME 120
PORTABLE CABLE
/-BULKHEAD
/ TERMINAL
-FRAME 105
2ND. DECK
FRAME 90
AFT
-FIXED CABLE
WATERTIGHT
BULKHEAD
3RD. DECK
FWD
V
LOAD
D-
LEGEND
BULKHEAD
TERMINAL
RISER
TERMINAL (R.T.)
CONNECTION
TERMINAL (C.T.)
Figure 3-4. Typical power run.
103.140
I casualty power distribution systems. If one
terating plant fails, a remote switchboard
L be connected by the bus tie to supply power
m the generator or generators that have not
led.
If a circuit or switchboard fails, the vital
ds can be transferred to an alternate feeder
. source of ship's service power by means of a
nsfer switch near the load.
If both the normal and alternate sources of
ship's power fail because of a casualty to
generator, switchboard, or feeder, the vital
iliaries can be shifted to an emergency feeder
t receives power from the emergency switch-
rd.
If the ship's service and emergency circuits
, temporary circuits can be rigged with the
ualty power distribution system and can be
d to supply power to vital auxiliaries if any
the ship's service or emergency generators
be operated.
The casualty power system includes suitable
lengths of portable cable stowed on racks through-
out the ship. Permanently installed casualty
power bulkhead terminals form an important
part of the casualty power system. They are
used to connect the portable cables on opposite
sides of bulkheads, so that power may be trans-
mitted through compartments without loss of
watertight integrity; also included are perma-
nently installed riser terminals between decks
(fig. 3- 5 A). The vital equipment selected to
receive casualty power will have a terminal box
(mounted on or near the equipment or panel con-
cerned) connected in parallel with the normal
feeder for the equipment.
Sources of supply for the casualty power
system are provided at each ship's service
switchboard and emergency generator switch-
board (fig. 3-5B). A casualty power terminal is
installed on the back of the switchboard, or
switchgear group, and connected to the bus
ties through a 225- or 250-ampere AQB circuit
SHIPBOARD ELECTRICAL SYSTEMS
Figure 3-5. Casualty power terminals.
77.257
breaker. This circuit "breaker is connected be-
tween the generator circuit breaker and the
generator disconnect links so, that by pulling
the disconnect links, the generator may be
isolated from the switchboard and may be used
exclusively for casualty power purposes, if
desired.
Due to the inherent dangers of electric shock
involved with the rigging of casualty power
cables, you, as division officer or electrical
officer, should be thoroughly familiar with Nav-
Ships Technical Manual Chapter 9880 Section
El, Engineering Damage Control, and the casualty
control manual for your ship.
SWITCHBOARDS
The a.c. switchboards may consist of a
single section or of several sections physically
separated and connected by cables to form a
switchgear group* This arrangement of sections
provides greater resistance to damage caused
by shock and also provides a means to localize
damage and to remove damaged sections for
repairs or replacement.
The ship's service switchboard (fig. 3-6)
is housed in sheet-steel panels or enclosures
from which only the meters and ope rating handles
of the switches and circuit breakers protrude
to the front of the switchboard. This type of
construction is used for all a.c. distribution
systems and for the d.c. distribution systems
in some large ships. (Compare the ship's service
switchboards shown in figures 3-1 and 3-6.
Although there is a variety of designs for these
switchboards depending on the needs of the ship,
the switchboards basically function in the same
manner.)
36
Chapter 3 DISTRIBUTION SYSTEMS
77.166
Figure 3-6. Ship's service switchboard.
The switchboard equipment is grouped to
form a number of units, each unit complete
with a separate front panel and all the required
devices such as controls on the a.c. generator
control unit. In addition, there is an a.c. bus tie
unit, a power distribution unit, and a lighting
distribution unit. A number of units mounted
on a common base comprise a section or several
sections which may be physically separated
and connected by cables to form a switchgear
group.
CIRCUIT BREAKERS
Circuit breakers have three fundamental pur-
poses: they provide circuit protection; they per-
form normal switching operations; and they
isolate a defective circuit while repairs are
being made.
Air circuit breakers are used in switchboards,
switch gear groups, and distribution panels.
The types, labeled according to size, on naval
ships are ACB, AQB, AQB-A, AQB-LF, NQB-A,
ALB and NLB. They are called air circuit breakers
because the main current-carrying contacts in-
terrupt in air.
Circuit breakers can be manually or elec-
trically operated. Some types may be operated
both ways, while others are restricted to one
mode.
Some larger circuit breakers have a drawout
feature (fig. 3-7) which allows the electrician's
37
SHIPBOARD ELECTRICAL SYSTEMS
IN NORMAL POSITION
B
IN WITHDRAWN POSITION
Figure 3-7. Large circuit breaker (ACB-1600).
77.258(.259)
mate to perform maintenance, tests and in-
spections with greater ease. Smaller breakers
(fig. 3-8) can be removed from the switchboard
by loosening the mounting screws and pulling
the breaker from the board.
An explanation of different circuit breakers
will not be complete without including a brief
description of selective tripping features and
their uses.
Selective Tripping
Selective tripping of circuit breakers permits
isolation of a faulty section of the system and,
at the same time, maintains power to as much
of the system as possible. Selective tripping
(coordination of the time-current characteristic
of circuit breakers) is normally obtained by a
mechanical, short time-delay feature of the
circuit breakers so that the breaker closest
to the fault will open first, and the breaker
farthest from the fault and closest to the generator
will open last.
The short time-delay feature can be varied
with limitations. The generator circuit breaker,
which is closest to the power source, has the
maximum continuous cur rent- carrying rating,
the highest available short-circuit current rating,
and the maximum short time-delay trip to ensure
that the generator breaker will be the last
breaker to trip. However, the generator breaker
will trip, within the tolerance of the breaker, on
the generator short circuit current at some
definite interval of time.
A portion of a distribution system with circuit
breakers employing selective tripping is illus-
trated in figure 3-9. The so-called instantaneous
tripping time is the minimim time required for
a breaker to open and clear a circuit when the
operation of the breaker is not intentionally
38
Chapter 3 DISTRIBUTION SYSTEMS
OPERATING HANDLE SHOWN 4. COVER SCREWS
IN LATCHED POSITION
AMPERE RATING MARKER 5. BREAKER NAMCPLATE
MOUNTING SCREWS 6. COTTER KEY HOLE
77.241
igure 3-8. -Complete front view of an AQ3-A250
circuit breaker.
elayed. Each circuit breaker will trip in less
lan 0.1 second (almost instantaneously) when
le current exceeds the instantaneous trip current
etting of the breaker. In a shipboard selective
ripping power system the individual circuit
reakers (generator, bus tie, shore power or
seder breakers) differ from each other depending
n:
1. The available load current
2. The available short circuit current
3. The tripping time band and trip current
settings selected
Bus tie circuit breakers are usually set to
:ip after a prescribed time delay (less than
le generator circuit breaker time delay), at a
urrent that is nearest to, but not less than
50% of the bus tie breaker coil rating (for
multigenerator switchgear groups) or at a current
nearest to, but not more than 80% of the generator
breaker short time-delay setting (for single
generator switchgear groups). Instantaneous trip-
ping is not normally used on bus tie circuit
breakers.
For currents less than the instantaneous trip
current setting, the circuit breakers for selective
tripping are constructed to cause an intentional
delay in the operation of the breaker. The tirnv?
delay is greater for small currents than for
large currents and is therefore known as an
inverse time delay. The current that will trip
the AQB load circuit breaker instantaneously and
clear the circuit will not trip the ACB feeder
circuit breaker unless the current flows for a
greater length of time. The same sequence
of operation occurs for the other groups of
circuit breakers in the system which are adjusted
for selective tripping. The difference between the
tripping times of the breakers is sufficient to
permit each breaker to trip and clear the circuit
before the next breaker starts to operate.
Assume that a fault or defect develops in
the cable insulation at point A (fig. 3-9) and
allows an overcurrent to flow through the AQB
load circuit breaker and the ACB feeder circuit
breaker. The AQB load breaker will open the
circuit and interrupt the current in an interval
of time that is less than the time required to
open the ACB feeder circuit breaker. Thus,
the ACB feeder breaker will remain closed when
the AQB breaker clears the circuit. However,
if the fault current should exceed the interrupting
capacity of the AQB load breaker (for example,
an excess of 10,000 amperes), this breakerwould
be unable to interrupt the fault current without
damage to the breaker. To prevent damage to the
AQB load breaker, the ACS feeder breaker (on
switchboard IS) serves as a BACK UP breaker
for the AQB load breaker and will open almost
instantaneously.
A fault at point B with overcurrent would
trip the ACB feeder breaker in time but not
the ACB generator breakers or bus tie breakers,
which require longer time intervals in which
to trip. A fault at point C with overcurrent would
trip both ACB bus tie breakers. A fault at D
with overcurrent on switchboard IS would trip
the associated ACB generator breakers. In each
case, the faulty section of the system is isolated,
but power is maintained to as much of the system
as possible with respect to the location of the
fault.
39
SHIPBOARD ELECTRICAL SYSTEMS
1SG
GENERATOR
1S
SWITCHBOARD
TYPE ACB ox
FEEDER BREAKERS )
2SG
GENERATOR
YPE ACB GENERATOR
BREAKERS
TYPE ACB BUS TIE
BREAKERS
-X-
-X-
SHORE POWER
TYPE AQB
LOAD
BREAKER
TO LOAD
Figure 3-9. Selective tripping of circuit breakers.
77,
Tl^e attainment of selective tripping requires
careful coordination of time- cur rent character-
istics fQr the different groups of circuit breakers.
For example, if the system illustrated in figure
3-9 is operating split plant (bus ties open) and
if the time-current characteristics of the ACB
feeder breaker and the ACB generator breaker
were interchanged, a fault at B with overcurrent
would trip generator iSG.off the line but would
leave the feeder connected to the switchboard.
This action would disconnect power to all equip-
ment supplied by switchboard IS and also would
not isolate the faulty section. Therefore, NO
UNAUTHORIZED CHANGES should .be made to
circuit breaker trip settings because these
changes may completely disrupt the scheme
of protection based on selective tripping.
A circuit breaker should NEVER be removed
from a switchboard without prior approval of
the electrical or engineer officer, and then only
after a thorough review of the applicable technical
manual, and Chapte/ 9600 of NavShips Technical
Manual.
You should NEVER work on any circuit
breaker, regardless of type, until you ensure
that the circuit is open. Remember that cert;
terminals may have voltage applied to them -si
though the breaker is open. Aboard ship, pOY
may be supplied to either end of the circ
breaker.
BUS BARS
Bus bars (fig. 3-10) are heavy, rugged metal
conductors usually insulated with a nonconduct:
paint and are used to carry the large general
loads within the switchboards.
DISCONNECT .LINKS
Disconnect links (fig. 3-11) are devices us
in switchboards to isolate a generator, a switc
board section or a bus tie whenever equip mt
has been damaged or whenever maintenance
required.
Disconnect links are connected in the lar
bus bars and are designed to carry the enti
current of the bus.
40
Chapter 3 DISTRIBUTION SYSTEMS
BUS BARS
BUS BARS
Figure 3-10. Opened rear view of ship's service switchboard.
27.353X
When work is to be performed on a circuit
eaker, the disconnect link is opened. However,
>u must remember that control power in MOST
stallations will still be available at the circuit
'eaker; therefore, the fuses for these devices
list be pulled before you start to work. These
ses are usually located on the back of the
fitchboard and are readily accessible.
The screw-type disconnecting links (fig. 3-12)
e normally located in the rear of the switch-
board and are operated by means of an insulated
wrench. The disconnect links must be tightened
firmly in both the * ' open' ' and " closed' 'positions.
CAUTION: Do NOT operate a disconnect link
when there is current flowing through the link.
MONITORING DEVICES
Watch stander s must have the ability to monitor
the equipment for which they are responsible. In
41
SHIPBOARD ELECTRICAL SYSTEMS
HINGE
BLOCK
CROSS-HEAD
PIN
BACKING
PLATE
LOCKING
SPRING
CONTACT
BLOCK
INSULATED
BASE
77.2
Figure 3-11. Disconnect links.
the electrical distribution system nany of the
monitoring devices are located on the switch-
boards. Meters, located on the face of the
switchboard, (fig. 3-13) monitor speed (fre-
quency), voltage, amperage, phase and speed
relation (synchroscope) of two generators being
paralleled. Indicator lights for ground detection
and breaker position are also located on the
switchboard.
CONTROL DEVICES
Switchboards also contain the devices neces-
sary to control the speed of the prime mover
(frequency) and the voltage.
The speed of the prime mover (either diesel,
steam turbine, or gas turbine) is controlled by
a switch, located on the front of the switchboart
which operates a governor motor located c
the prime mover.
The voltage is controlled by turning a sma
rheostat, located on the switchboard, which inserl
or removes resistance in the voltage reg^latoi
PROTECTIVE DEVICES
i
i
t
1
c
c
3
Along with the previously discussed trippin a
devices incorporated in the circuit breaker*
the switchboard contains other safety and pro
tective devices. a
s
On ships with a.c. ship's service powe t
systems where the generators are operate 1
42
Chapter 3 DISTRIBUTION SYSTEMS
- DISCONNECT LINKS
Figure 3-12.- Rear view ship's service switchboard.
77.256X
)arallel, each generator control unit has a
3rse power relay. The relay should trip
generator circuit breaker in approximately
ieconds with reverse power equal to 5 percent
le generator rating.
Reverse power relays trip the generator
:uit "breaker to prevent motoring the generator.
3 protection is provided for the prime mover
its generator.
n motoring, the faulty generator set will
as an additional load for the good generator
Motoring can result from a deficiency in
prime mover input to the a.c. generator.
j deficiency (insufficient torque) can be caused
by loss of steam or low steam to the turbine,
lack of fuel to the diesel engine or gas turbine,
or other factors which affect the operation of the
prime mover. In the absence of reverse power
protection, when the input to the generator
falls below that needed to maintain required
generator speed, power is taken from the ship's
service power system, and the generator acts
as a motor driving the prime mover.
Fuses are used to protect the monitoring
and control devices.
SHORE POWER
CONNECTION
The number and locations of shore power
connections vary on different types of ships.
43
SHIPBOARD ELECTR5CAL SYSTEMS
27.35
Figure 3-13* Typical meters on switchboards.
Shore power connections are provided at, or
near, a suitable weather-deck location to which
portable cables from the shore or from ships
alongside can be connected to supply power
for the ship's distribution system when the
ship's service generators are not in operation.
Shore power connections are connected to
cables which terminate at circuit breakers located
on the switchboards. A typical arrangement for
shore power circuit breakers on smaller vessels
is shown in figure 3-9.
BUS TRANSFER
EQUIPMENT
Bus transfer equipment is installed on switch-
boards, at load centers, distribution panels, or
on loads that are fed by both normal and alternat
and/or emergency feeders. See fig. 3-14. Thl
equipment selects either the normal or alternat
source of the ship's service power, or obtain
power from the emergency distribution systen
if an emergency feeder is also provided.
Automatic bus transfer (ABT) equipment 1;
used for loads that require two power supplies
except for cold-ship starting of auxiliaries an
fire pumps, which have manual bus transfe
equipment. On the steering power equipment
which is provided with a normal, alternate, an
emergency power supply either automatic 01
manual bus transfer equipment is used to selec
between the normal and alternate supplies* Th(
automatic bus transfer equipment is used t
select between the ship's service and emergenc]
supplies. On some ships only two sources o:
steering power are provided normal and emer-
gency.
Chapter 3 DISTRIBUTION SYSTEMS
AST
Figure 3-14. Emergency switchboard (showing ABT's).
77.324X
LOAD CENTERS AND
POWER PANELS
Load centers and power panels are supplied
om the switchboard, which is a branching out
r the electric power distribution system. Power
riginates at the power supply (fig. 3-15) and
isses through a generator circuit breaker lo-
tted in the main switchboard. On larger ships
>wer can go to load centers (fig. 3-16) for further
stribution to loads. Smaller ships usually in-
>rporate the load centers as a part (sometimes
called switchgear groups) of the main switchboard
(fig. 3-17). Figure 3-18 shows a typical power
panel.
INTERIOR COMMUNICATION
DISTRIBUTION
Shipboard interior communications (1C) sys-
tems are defined as anything that causes an
audible or visual signal to be transferred within
SHIPBOARD ELECTRICAL SYSTEMS
SOME
LARGER
LOADS
LOAD CENTER
POWER PANEL
LOADS
MAIN
SWITCHBOARD
LOAD CENTER
POWER PANEL
Figure 3-15. Line diagram of power distribution (larger ships).
27.61
or between the compartments of a ship. They
provide a means of exercising command within
a ship and include voice interior communications,
alarm, warning, ship control, entertainment,
gyrocompass, and plotting systems. Although
many of the weapons and fire control circuits
are supplied by the 1C switchboards, these
systems are not part of the 1C responsibility.
1C SWITCHBOARD
The 1C switchboard is the nerve center of
the interior commani cations system. All interior
communication and some fire control circuits,
including fire control electronic systems, are
energized through the 1C switchboard,
To obtain maximum protection, most 1C
switchboards are installed below the waterline
and are energized from a normal, an alternate,
and an emergency power supply to ensure con-
tinuous service.
In large combatant ships there are two mail
1C switchboards. One switchboard is locatec
in the forward 1C room, and the other switch-
board is located in the after 1C and gyro room,
Thus, each system or equipment receives its
normal supply from the nearer 1C switchboard
The after main 1C switchboard is usually arrangec
similarly to the forward main board, except tha (
in the after 1C room some of the special busef
such as the controlled-frequency bus may &
omitted.
In the older ships, separate 1C and actior
cutout (ACO) switchboards are installed. In nev
construction ships, 1C switchboards are composed
of power control distribution and ACO sections,
The latest type 1C switchboard is the front-
service 1C board (fig. 3-19) which is constructed
so that installation, operation, and maintenance
46
Chapter 3 DISTRIBUTION SYSTEMS
77.166X
Figure 3-16. Load center switchboard.
an be accomplished entirely from the front of
le switchboard. The front-service design uses
box-type construction with hinged front panels,
witches and fuse holders up to 60-ampere
apacity and other relatively light items are
lounted on the hinged panels, while heavier items
re mounted behind removable panels.
Terminal boards within the switchboard en-
losure provide for termination of all ship's
cables except for a few of the larger cables,
which run directly to their associated switches
and fuse holders. All wiring between the terminal
boards and the equipment mounted on both the
hinged and stationary panels is installed by the
switchboard manufacturer to permit free swinging
of the panels without interference from, or
damage to, the wiring harness.
To reduce the rigidity of the switchboard
and to permit separate movement of panels
SHIPBOARD ELECTRICAL SYSTEMS
LOADS
MAIN SWITCHBOARD
27.66
Figure 3-17. Line diagram of power distribution
(smaller ship).
during shock, cables are used instead of horizon-
tal buses for connections between or among
switchboard sections. Some vertical buses may
be used, however, to supply sections of the
individual panel.
The principal advantage of the front- service
1C switchboard is that it can be mounted against
a bulkhead because no access space is required
in the rear of the board. This feature results
in a saving of space, which is most important
aboard ship.
The action cutout (AGO) section permits
isolation of various portions of 1C systems
and in addition, allows transfer control of certain
systems from one station to another. Separate
switchboards are usually provided for specialized
systems such as the sound-powered telephone
system.
In older combatant vessels the ACO switch-
board (one or more sections) is located in the
central section, which also functions as damage
control central. On new construction ships,
damage control central is combined with engi-
neering central (log room) and is located nearer
to the engineering plant and farther from the
1C room. However, the ACO section is located
in the 1C room and is part of the 1C switchboard.
A front-service ACO section is shown in
figure 3-20. Drawout switch units are utilized
with each unit ..^eorporating the associated fuse
holders and overload indicators.
27.355
Figure 3-18. Typical power panel.
1C SWITCHBOARD
POWER SUPPLY
The power distribution systems and arrange-
ments of buses of 1C switchboards vary widely
in different ships, dependent of the size and
mission of the ship, the main power system,
and the fire control (FC) system. The following
discussion describes the general principles of
a typical 1C switchboard power supply.
The forward main 1C switchboard is supplied
with power from as many sources as possible,
The power supply usually consists of (1) a
normal supply from a main power distribution
Chapter 3 DISTRIBUTION SYSTEMS
AUTOMATIC BUS TRANSFER
27.270
Figure 3-19. Front-service main 1C switchboard.
iwitchboard of the forward machinery group,
2) an alternate supply from a main power dis-
ribution switchboard of the after machinery
;roup, and (3) an emergency supply from the
earer emergency-distribution switchboard.
The normal 3-phase, 450- volt, 60- Hz power
upply is obtained from the forward main ship's
ervice distribution switchboard through an ACB
ircuit breaker on that board. The 450-volt supply
3 connected to a 450-volt bus on the main 1C
witchboard through the bus-transfer switch
\BT), as shown in figure 3-14.
The 450-volt bus energizes the various 450-
olt, 60-Hz circuits through individual switches
and fuses. In this installation the 450/120-volt
60-Hz transformer bank is energized directly
from the 450-volt bus through fuses. However, in
some installations the transformers are energized
through a switch and fuse combination.
The 1C transformer bank is connected delta-
delta in order to operate open-delta in case of a
casualty to one transformer (discussed in chapter
5 of this training manual). When operating open-
delta, strip the switchboard of all but the vital
circuits. The load can be reduced as necessary
by opening the switches of less essential circuits.
In some ships in which the emergency power
is extremely small, the main 120-volt a.c. bus
49
SHIPBOARD ELECTRICAL SYSTEMS
Figure 3- 20. -Front view of front-service switchboard.
55.311
.*& tfZ% l FFS?Zi ?> contactors open automatic^ upon tra^e,
srigf s sru s to to ^SLSS Sr^^ssa.^; s-ss
. to* ~i BW1 o h e 9 "jss; Js^stg^^jsssssR
Chapter 3 DISTRIBUTION SYSTEMS
l-l(|)-450/l20V-60 r b
TRANSFORMER
ALT. PWR SUPPLY
I20V-60O-I(1) FROM
1.1.1 1.1
Figure 3-21. Local 1C switchboard.
140.18
1C and FC buses have been opened to reduce section may be supplied by a motor generator
load, the contactors supplying these buses or a static power supply which receives its power
closed again. from the 450-volt, 60-Hz bus at its associated
There are two 400-Hz closely regulated bus switchboard. The 120-volt, 400-Hz section of
tions 450-volt and 120-volt. The 450-volt each switchboard receives its power from a
51
SHIPBOARD ELECTRICAL SYSTEMS
delta-delta connected bank of transformers, which
are connected to the respective 450-volt, 400 Hz
sections. A d.c. section receives its power supply
from a 120-VDC rectifier.
LOCAL 1C
SWITCHBOARDS
A local 1C switchboard is usually provided
in each engineroom to energize local 1C circuits.
The normal supply for each switchboard is from
the nearer main 1C switchboard. The emergency
supply for each switchboard is from a local
emergency lighting circuit. This arrangement
provides the switchboard with the same power
backup as that of the main 1C switchboard.
However, in case of loss of power at the main
1C switchboard or damage to the connecting
cable, the local switchboards can still be energized
from an alternate source. Automatic bus transfer
switches are provided on the 1C switchboards in
the engineroom and steering gear room on
newer ships to minimize interruptions if the
normal power source is lost. Action cutout
switches are provided to disconnect equipment
that is connected to local transmitters.
A local 1C switchboard (fig. 3-21) is usually
installed in each steering gear room to energize
all circuits associated with steering-order and
rudder-angle indicator systems. The normal
supply for this switchboard is from the steering-
power transfer switchboard through a local trans-
former. An alternate supply is taken from a
local emergency lighting circuit to provide power
if the normal supply is lost.
CLASSIFICATION
OF CIRCUITS
1C circuits are classified according to im-
portance and to readiness.
Each 1C circuit is classified into one of the
following three groups according to its im-
portance.
VITAL CIRCUITS are those circuits th
are essential to the fighting effectiveness
the ship. The loss of a vital circuit, such;
the gyrocompass system, would seriously irnpa
fighting effectiveness.
SEMIVITAL CIRCUITS are those circui
that are very important but not essential
fighting effectiveness. The loss of a semivit
circuit, such as the auxiliary battle telepho
system, would impair fighting effectiveness le
than the loss of a vital circuit.
NON VITAL CIRCUITS are those circuits tt
are not essential to fighting effectiveness. T
loss of a nonvital circuit, such as the boile
feed signal system, would not impair fighti
effectiveness.
Each 1C circuit is classified into one oft
following four groups according to its reading
CLASS 1 CIRCUITS are those that are esse
tial to the safety of the ship. These circuits a
energized at all times.
CLASS 2 CIRCUITS are those that (along ^
class 1 circuits) are essential to ship contK
These circuits are energized during the prep;
ration period for getting underway, while stand!
by, while underway, and until the ship is seem
after coming to anchor.
CLASS 3 CIRCUITS, or BATTLE CIRCUIT
are those that (along with class 1 and class
circuits) are essential to complete interior co:
trol. These circuits are energized during co:
dition watches.
CLASS 4 CIRCUITS are the convenience ci
cuits that are energized only when require
such as ship's entertainment system.
Supply switches on 1C switchboards are colon
as shown to identify readily the class of circui
Class 1. . .Yellow continuously energized
Class 2. . .Black underway circuits
Class 3. . .Red battle circuits
Class 4. . .White convenience circuits
52
CHAPTER 4
MOTORS AND CONTROLLERS
Electric motors and controllers are a vital
rt of a ship's operating ability. They provide
3 mechanical power for many purposes ranging
Dm large horsepower pumps and compressors
small fractional horsepower motors for fans
d portable tools Most electric motors are
nnected to the power supply lines through a
ntr oiler (starter) which controls and protects
3 motor.
In this chapter we shall describe the basic
sration of motors, their construction, appli-
tion, and the control devices associated with
DC MOTORS
There is very little difference in basic con-
uction between a d.Co motor and a doC generator
r, 4-1). A generator is rotated by a prime
>ver to convert mechanical energy to electrical
*rgy, whereas a motor is connected to a source
electrical power and con verts electrical energy
mechanical energy. A d.c. generator may
made to function as a motor if you apply
suitable source of direct voltage across the
:mal output electrical terminals as described
no-break power supplies.
The operation of a d.c. motor depends on
principle that a current-carrying conductor
ced within, and at right angles to, a magnetic
Id tends to move at right angles to the direction
iie field, as shown in figure 4-2.
The magnetic field between the north and
south poles of a magnet is shown in figure
!A. The lines of force comprising the field
end from the north pole to the south pole,
yross section of a current-carrying conductor
re) is shown in figure 4-2B. The plus sign
bin the wire indicates that the electron flow
is away from the observer. The flux loops
counterclockwise around the wire, as shown.
This follows the left-hand rule which states
that if the conductor is grasped in the left
hand with the thumb extended in the direction
of the current flow, the fingers will curve around
the conductor in the direction of the magnetic
flux.
If the conductor (carrying the electron flow
away from the observer) is placed between
the poles of the magnet, as in figure 4-2C,
both fields will be distorted. Above the wire
the field is weakened, and the conductor tends
to move upward* The force exerted depends on
the strength of the field between the poles
and on the strength of the current flowing through
the wire.
If the current through the conductor is re-
versed, as in figure 4-2D, the direction of the
flux loops around the wire is reversed. The
field below the conductor is now weakened, and
the conductor tends to move downward. This
force, which acts on the conductor under these
conditions, is directly proportional to the strength
of the magnetic field, the magnitude of the current,
and the length of the conductor.
Since a motor is a rotating machine, the force
exerted on the armature conductor is expressed
in torque as measured at the motor shaft. The
torque for a given motor is therefore directly
proportional to the armature current and the
strength of the magnetic field.
The various types of d.c. motors (fig. 4-3)
are identified by the way the field coils are
connected. Each type has characteristics that
are advantageous under given load conditions.
SHUNT MOTORS
In figure 4-3A the field coils are connected
in parallel with the armature circuit. This type
SHIPBOARD ELECTRICAL SYSTEMS
END BELL
AIR OUTLET
COMMUTATOR
ARMATURE
COIL
TERMINAL
BOX
BEARING OUTER
' CAP
BRUSH STUD
INSULATOR
BRUSH STUD
MAIN FIELD COIL
ARMATURE CORE
MAIN POLE PIECE
FRAME
BAFFLE PLATE
GREASE SLINGER
END BELL
Figure 4rl. D.c. motor.
motor, with constant potential (voltage) applied,
develops variable torque at an essentially constant
speed, even under changing load conditions. Such
* fOUnd in ^achine shop motors and
73.161
SERIES MOTORS
In figure 4-3B the field coils are connected
in series with the armature circuit. This type
motor, with constant potential applied, develop
variable torque, but its speed varies wideli
54
Chapter 4 MOTORS AND CONTROLLERS
FIELD FLUX
A
FLUX AROUND
CONDUCTORS
B
MOTION UP
C
MOTION DOWN
D
236,359
.gure 4-2. Force acting on a current-carrying
conductor in a magnetic field.
ider changing load conditions. That is, the
>eed is low under heavy loads but becomes
icessively high under light loads. Series motors
e commonly used to drive electric cranes,
dsts, winches, and certain types of vehicles
>r example, electric trucks). Series motors
e used extensively to start internal combustion
igines. CAUTION: A series motor that is run
.thout load will destroy itself by overspeed.
IMPOUND MOTORS
Figure 4-3C shows a compound motor a
mpromise between shunt and series motors,
le set of field coils is connected in parallel
th the armature circuit, and the other set
field coils is connected in series with the
mature circuit. A compound motor develops
. increased starting torque over that of the
.unt motor and has less variation in speed
an the series motor. Shunt, series, and com-
und motors are all d.c* motors designed
operate from constant-potential, variable-
rrent d.c. sources.
'ABILIZED SHUNT MOTORS
Figure 4-3D shows a stabilized shunt motor a
jht series winding in addition to the shunt
SHUNT
FIELD
SERIES FIELD
ARMATURE
ARMATURE
SHUNT
A
SERIES
ARMATURE
SERIES
FIELD
ARMATURE
COMPOUND
C
STABILIZED SHUNT
D
236.356
Figure 4-3. Schematic diagrams of four types
of d.c. motors.
field. The action is similar to ordinary shunt
motors except stabilized shunt motor shave better
torque characteristics with less field iron and
therefore are lighter in weight.
AC MOTORS
The majority of Navy ships utilize a.c, motors
for electromechanical energy for several reasons.
As previously discussed, most ship's service
generators produce alternating current, thus
making it readily available. Also ac. motors
are generally less expensive than d.c, motors.
Most types of a.c. motors do not employ brushes
and commutators, thereby eliminating dangerous
sparking as well as the many problems of main-
tenance and wear.
55
A.c. motors are designed for use with poly-
phase or single-phase power systems and come
in many different sizes, shapes, and ratings. We
cannot possibly cover all a.c. motors in this
chapter. Consequently, we shall deal with the
operating principles and applications of the four
most common types found aboard ship: the
polyphase induction motor and the single phase
motors which include the split-phase motor,
the capacitor motor, and the universal motor*
So that you will better under stand the operating
principles of polyphase induction motors, let us
briefly discuss the a.c. theory. Referring to
figure 4-4 you will see the manner in which a
rotating field is produced by stationary coils,
or windings, when they are supplied by a 3-phase
power source. For purposes of explanation, rota-
tion of the field is developed in figure 4-4 by
"stopping" it at six selected positions, or instants.
These instants are marked off at 60 intervals
on the sine waves, representing currents in the
three phases A, B, and C.
At instant (1) the current in phase B is
maximum positive. (Assume plus 10 amperes
in this example). Current is considered to be
positive when it is flowing out from a motor
terminal. At the same time (instant 1) current
flows into the A and C terminals at half value
(minus 5 amperes each in this case). These
currents combine at the neutral (common con-
nection) to supply plus 10 amperes out through
the B phase.
The resulting field at instant (1) is established
downward and to the right, as shown by the arrow
NS. The major portion of this field is produced
by phase B (full strength at this time) and is
aided by the adjacent phases A and C (half
strength). The weaker portions of the field
are indicated by the letters "n" and "s."
The field is two-pole extending across the space
that would normally contain the rotor.
At instant (2) the current in phase B is
reduced to half value (plus 5 amperes in this
example). The current in phase C has reversed
its flow from minus 5 amperes to plus 5 amperes
and the current in phase A has increased from
minus 5 to minus 10 amperes.
The resulting field at instant (2) is now
established upward and to the right, as shown
by the arrow NS. The major portion of the field
is produced by phase A (full strength), and the
weaker portions are produced by phases B ,ind
C (half strength).
At instant (3) the current in phase C is plus
10 amperes and the field extends vertically
upward; at instant (4) the current in phase B
becomes minus 10 amperes, and the field extends
upward and to the left; at instant (5) the current
in phase A becomes plus 10 amperes, and the
field extends downward and to the left; at instant
(6) the current in phase C is minus 10 amperes,
and the field extends vertically downward. Instant
(7) (not shown) corresponds to instant (1) when
the field again extends downward and to the right,
Thus, a full rotation of the two-pole field
has been accomplished through one full cycle oi
360 electrical degrees of the 3-phase currents
flowing in the windings.
POLYPHASE INDUCTION
MOTORS
The driving torque of both d.c. and a.c,
motors is derived from the reaction of current-
carrying conductors in a magnetic field. You
will recall that in the d.c, motor the magnetic
field is stationary and the armature, with its
current-carrying conductors, rotates. The cur-
rent is supplied to the armature through a
commutator and brushes.
In induction motors (fig. 4-5) the rotor cur-
rents are supplied by electromagnetic induction,
The stator windings (coils) receive the 3-phase
power and produce the previously mentioned ro-
tating magnetic field. The magnetic field rotates
continuously at constant speed (synchronous)
regardless of the load on the motor. The rotor
is not connected electrically to the power supply,
The induction motor derives its name from the
fact that electromagnetic induction takes place
between the stator and the rotor under operating
conditions* The magnetic revolving field pro-
duced by the stator cuts across the rotor con-
ductors, thereby inducing a voltage in the
conductors. The induced voltage causes rotor
current to flow. Hence, motor torque is developed
by the interaction of the rotor's magnetic field
and the stator 's revolving magnetic field.
Most larger a.c. motors which are used on
naval ships are polyphase (3-phase) induction
motors.
Figure 4-6 shows the rotor and stator of a
typical polyphase induction motor.
56
<N
si
<D
CO
<D
S3
bO
s
CD
a
4.
0)
57
BALL BEARING
BEARING
OUTER CAP
-AIR CONE
BALANCING DISK
LOADING
SPRING
END BELL
BEARING INNER
CAP
DRIPROOF COVER
AIR OUTLET
TERMINAL BOX
LEAD CLAMP
TERMINAL BOX
END BELL
INLET
STATOR COIL
ROTOR
FAN BLADE
STATOR CORE
FRAME
ROTOR CORE
BEARING INNER CAP
BALL BEARING
GREASE SLINGER
BALANCING DISK
BEARING
OUTER CUP
Figure 4-5 3-phase induction motor
73.161
SINGLE-PHASE
MOTORS
Single-phase motors, as their name implies,
operate on a single-phase power supply. These
motors are used extensively in fractional horse-
power sizes in commercial and domestic appli-
cations. The advantages of using single-phase
motors in small sizes are that they are less
expensive to manufacture than other types, and
they eliminate the need for 3-phase a.c* lines,
Single-phase motors are used in interior com-
munications equipment, fans, refrigerators, port-
able drills, grinders, and so forth.
A single-phase induction motor with only one
stator winding and a cage rotor is like the
58
A. ROTOR
B. STATOR
73.147-77.77
Figure 4-6. Typical polyphase induction motor
(stator and rotor).
3-phase induction motor with a cage rotor except
that the single-phase motor has no revolving
magnetic field at start, hence, no starting torque.
However, if the rotor is brought up to speed
by external means, the induced currents in the
rotor will cooperate with the stator currents
to produce a revolving field. This causes the
rotor to continue to run in the direction in
which it was started.
Several methods are used to provide the
single-phase motor with starting torque. These
methods identify the motor as split phase, capaci-
tor, etc. Another single-phase motor, which
WQ shall discuss later, is the a.c. series motor
(universal).
SPLIT- PHASE MOTOR
The split-phase motor (fig, 4-7A) has a
stator composed of slotted laminations which
contain an auxiliary (starting) winding and a
running (main) winding. The axes of these two
windings are displaced by an angle of 90 elec-
trical degrees. The starting winding has fewer
turns and smaller wire than the running winding;
hence, the starting winding has higher resistance
and less reactance. The main winding occupies
the lower half of .the slots, and the starting
winding occupies the upper half. The two windings
are connected in parallel across the single-
phase line which supplies the motor. The motor
derives its name from the action of the stator
during the starting period. The single-phase
stator is split into two windings (phases), which
are displaced in space by 90, and which contain
currents displaced in time phase by an angle
of approximately 15 (fig. 4-7B). In the starting
winding, current I s lags the line voltage by
approximately 30 and is less than the current
in the main winding because of the higher im-
pedance (AC resistance) of the starting winding.
In the main winding, the current, 1^ lags the
applied voltage by approximately 45. The total
current, In ne , during the starting period is
the vector sum of I s and I M .
At start, these two windings produce a mag-
netic revolving field which rotates around the
stator air-gap at synchronous speed. As the
rotating field moves around the air gap, it cuts
across the rotor conductors and induces a voltage
in them, which is maximum in the area of highest
field intensity and, therefore, is in phase with
the stator field. The rotor current lags the rotor
voltage at start by an angle that approaches
90 because of the high rotor reactance. The
interaction of the rotor currents and the stator
field causes the rotor to accelerate in the
direction in which the stator field is rotating.
During acceleration the rotor voltage, current,
and reactance are reduced, and the rotor currents
come closer to an inphase relation with the
stator field.
When the rotor has come up to approximately
75 percent of synchronous speed, a centrifugally
operated switch (fig. 4-8) disconnects the starting
winding from the line supply, and the motor con-
tinues to run on the main winding alone. There-
after, the rotating field is maintained by the
interaction of the rotor magnetomotive force and
the stator magnetomotive force. These two mmf's
are pictured as the vertical and horizontal
vectors respectively in the schematic diagram
in figure 4-7C.
59
SHIPBOARD ELECTRICAL SYSTEMS
"LINE
1
CENTRIFUGAL
SWITCH
f
SINGLE-PHASE
SO
JRCE
-J
MAIN
i
\
WINDING
noorv I
STARTING
WINDING
LINE
CIRCUIT
VECTORS FOR
STARTING
ROTOR MMF
STATOR MMF
RUNNING
ANALYSIS
Figure 4-7. Split-phase motor.
236.323
The stator field is assumed to be rotating
at synchronous speed in a clockwise direction,
and the stator currents correspond to the instant
that the field is horizontal and extending from
left to right across the airgap. The left-hand
rule for magnetic polarity of the stator indicates
that the stator currents will produce an N pole
on the left side of the stator and an S pole on
the right side. The motor indicated in figure
4-7C is wpund for two poles.
CAPACITOR MOTOR
The capacitor motor is single-phase and has
a capacitor in series with the starting winding.
An external view is shown in figure 4-9 with
the capacitor located on top of the motor. The
capacitor produces a greater phase displacement
of currents in the starting and running windings
than is produced in the split-phase motor. The
starting winding in the capacitor motor is made
of many more turns of larger wire than that
in the split-phase motor and is connected in
series with the capacitor. The starting winding
current is displaced approximately 90 from
the running winding current. Since the axes
of the two windings are also displaced by an
angle of 90, a higher starting torque is produced
than that in the split-phase motor. The starting
torque of the capacitor motor may be as much
as 350 percent of the full-load torque.
If the starting winding is cut out after the
motor has increased in speed, the motor is
60
Chapter 4 MOTORS AND CONTROLLERS
RUNM1NG OR
MAW WINDING
END BELL
END BELL
CENTRIFUGAL SWITCH
STATOR
Figure 4-8. Exploded view of a split-phase motor.
27.317
Figure 4-9. Capacitor motor.
236.324
called a CAPACITOR-START MOTOR. If the
starting winding and capacitor are designed
to be left continuously in the circuit, the motor
is called a CAPACITOR-RUN MOTOR. Electro-
lytic capacitors for capacitor-start motors vary
in size from approximately 80 microfarads for
1/8-horsepower motors to 400 microfarads for
1-horsepower motors. Capacitor motors of both
types are made in sizes ranging from small
fractional horsepower motor sup to approximately
10 horsepower. They are used to drive grinders,
drill presses, refrigerator compressors, and
other loads which require relatively high starting
torque. The direction of rotation of the capacitor
motor may be reversed by interchanging the
starting and winding leads.
UNIVERSAL MOTOR
A universal motor (fig. 4-10) can be operated
on either d.c. or single-phase a.c. Aboard Navy
ships, they are used extensively for portable
tools. The motor is constructed with a main
field connected in series with an armature. The
armature is similar in construction to any d.c.
motor. When electric power is applied, the mag-
netic force created by the fields will react with
the magnetic field in the armature and cause
rotation*
SHIPBOARD ELECTRICAL SYSTEMS
27*357
and uni-
Figure 4-10. Portable electric drill
versal motor parts.
CONTROLLERS
A controller is a device, or group of devices,
which connects or disconnects the power supply
to a motor. Most controllers also provide over-
load protection (overcurrent) for the motor. Some
controllers are designed to reverse and select
speeds on certain motors. Although controllers
are designed in many different ways, we shall
discuss only the basic fundamentals of controllers.
You will find more detailed information in NAV-
SHIPS Technical Manual, Chapter 9630, EM 3& 2,
NAVEDTRA 10546-D, and the manufacturer's
technical manual.
Controllers on naval vessels are either manual
or magnetic for both a.c. or d.c.
A MANUAL or nonautomatic controller (fig.
4-11) is operated by hand directly through a
mechanical system . The operator closes and opens
the contacts that normally energize and de-
energize the connected load. In a MAGNETIC
27,358
Figure 4-11. Manual controller.
controller these contacts are closed and opened
by electromechanical devices that are operated
by local or remote master switches. Magnetic
controllers may be semiautomatic or automatic,
DC CONTROLLERS
The starting of most d.c. motors, with the
exception of fractional horsepower sizes, requires
Chapter 4 MOTORS AND CONTROLLERS
i temporary insertion of resistance in series
yith the armature circuit to limit the high
n-rush current at standstill. Because of this
consideration, the starting resistance cannot be
jafely removed from the line until the motor
ias accelerated in speed and the counter electro-
notive force is of sufficient strength to limit
he current to a safe value. This is normally
tccomplished with a d.c. controller (fig. 4-12).
The connections for a motor controller with
me stage of acceleration is shown in figure
4-13. When the START button is pressed, the
path for current is from line terminal L2 through
the control fuse, STOP button, the closed START
button, and the line contactor coil LC to line
terminal LI. Current flowing through the con-
tactor coil (LC) causes the contactor to pull in
and close the line contacts, LCI, LC2, LC3, and
LC4.
When contacts LCI and LC2 close, motor-
starting current flows through the series field
SE, the motor armature A, the series relay
STARTING
RESISTORS
MAIN
CONTACTOR
ACCELERATION
CONTACTOR
OVERLOAD
DEVICE
27.318X
Figure 4-12.- A typical d.c. controller.
SHIPBOARD ELECTRICAL SYSTEMS
L2 rt
LC4
Figure 4-13. D.c. controller with one stage of acceleration.
77.140
coil SR, the starting resistor R, and the overload
relay coil OL. At the same time, the shunt
field winding SH, is connected across the line
and establishes normal shunt field strength. Con-
tacts LC3 close and prepare the circuit for the
accelerating contactor coil AC. Contacts LC4
close the holding circuit for the line contactor
coil LC. The START button can now be released.
The motor armature current flowing through
the series relay coil causes its contactor to
pull in, thereby opening the normally closed
contacts SR. As the motor speed picks up, the
armature current drawn from the line decreases.
At approximately 110 percent of normal running
current, the series relay current is not enough
to hold its contactor in; therefore, it drops
out and closes its contacts SR. These contacts
are in series with the accelerating relay coil
AC, causing it to pick up its contactor, closing
contacts ACI and AC2.
Auxiliary contacts ACI on the accelerating
relay keep the circuit to the relay coil closed
while the main contacts AC 2 shunt out the starting
resistor and the series relay coil. The motor is
then connected directly across the line, and the
connection will be maintained until the STOP
button is pressed.
If the motor becomes overloaded, the excessive
current through the overload coil (OL at the top
right of fig. 4-13) will open the overload contacts
(at the bottom of fig. 4-13) to disconnect the
motor from the line.
If the main contactor drops out because
of an excessive drop in line voltage or because
of a power failure, the motor will remain dis-
connected from the line until an operator restarts
it with the START pushbutton.
AC CONTROLLERS
Ac motors usually draw less power on starting,
therefore starting resistance is not normally
required on a.c. controllers. Most a.c. con-
trollers are coupled to their power supply by
across-line controllers. A typical 3-phase
across-line controller consists of a 3-pole main-
line contactor, two overload relays, mounting
panel, an enclosure with mechanical overload-
relay reset mechanism, and a master switch
(start- stop pushbutton), as shown in figure 4-14.
A schematic diagram of 3-phase a.c. across-
the-line magnetic controller with overload and
low voltage protection is shown in figure 4-15,
The motor is started by pushing the START
button (fig. 4-15). This action completes the
circuit from L3 through the control fuse, STOP
64
Chapter 4 MOTORS AND CONTROLLERS
Figure 4-14. Across-the-line, 3-phase, a.c. controller, pictoral view.
27.319X
TO 3 PH.
A.C.SUPPLY
10 A
CONTROL
FUSE
MOMENTARY
CONTACT
PUSHBUTTONS
77.132
rigure4-15. Ac. controller with low voltage and
overload protection, schematic diagram*
button, START button, the overload relay con-
tacts OL, and the contactor coil M to LI.
When the coil is energized, it closes line con-
tacts Ml, M2, and M3, which connect the full- line
voltage to the motor 9 The line contactor auxiliary
contact MA also closes and completes a holding
circuit to maintain the M coil energized after
the START pushbutton has been released.
The motor will continue to run until the
contactor coil is deenergized by the STOP push-
button, failure of the line voltage, or tripping
of the overload relay OL. Some larger a.c
motors might require a limiting (controller)
device in starting, which may be of the auto-
transformer type, the reactor controller type,
or the primary resistor type,
Controllers are grouped under one of the
following protective features: Low voltage pro-
tection, low voltage release, or low voltage
release effecto
SHIPBOARD ELECTRICAL SYSTEMS
Low- Voltage
Protection (LVP)
A low- voltage protection magnetic controller,
upon loss or excessive reduction of supply voltage,
disconnects the motor from the power supply
and keeps it disconnected until the supply voltage
returns to normal and the operator restarts the
motor. This protects the power supply from over-
load upon restoration of power. LVP is desirable
for auxiliaries which are not so essential that
they must be restarted immediately.
Low-Voltage
Release (LVR)
A low-voltage release magnetic controller,
upon reduction or loss of supply voltage, dis-
connects the motor from the power supply,
keeps it disconnected until the supply voltage
returns to normal, and then automatically re starts
the motor. Controllers with this feature are
used only for auxiliaries which must be restarted
immediately upon restoration of power.
Low-Voltage
Release Effect (LVRE)
A low-voltage release effect controller pro-
vides the same effect in manual controllers
as is obtainable in a low-voltage release type'
magnetic controller. That is, it will restart
automatically upon restoration of power.
A
B
C
AND SYMBOL
A
B
C
OR SYMBOL
J 1
B l 1
F
1 1
c l 1
H'h
OR CIRCUIT
77.35
Figure 4-17. OR symbol and circuit.
LOGIC CONTROLLERS
All control circuits employ logic. The basic
electrical controls use electrical and mechanics!
devices to perform their logic. In figure 4-16A
you can see that contacts a, b, and c mug
ALL be closed to energize the relay, there]]]
creating an output. The same transistor circui:
switch (electronic switch) can be used and is
represented by the logic symbol (AND) show
in figure 4-16B.
Another electrical circuit is shown in figure
4-17A. As you can see, EITHER a or b contact
can be closed thus energizing the relay anc
obtaining an output. The comparable logic symbol
(OR) is shown in figure 4-1 7B.
Using the characteristics of the AND and OR
logic symbols we shall discuss how they cat
be used in a logic controller.
B c
HHH
"-2
OUTPUT
AND CIRCUIT
77.356
Figure 4~16 AND symbol and circuit.
2ND-
3RD'
AND
LOGIC
SYMBOL
AMPLIFIER
ON A DECK
ACCESS
DOOR SHUT
77.370
Figure 4-18. Basic logic circuit.
Chapter 4 MOTORS AND CONTROLLERS
One common application of logic control that
is being incorporated on newer ships is the
elevator system. Since this system is large
with many symbols, we shall show only a small
portion.
Let us assume that the elevator platform is
on the third deck and that you require it on
the main deck. Refer to figure 4-18* Three
conditions must be met before the elevator can
be safely moved. These conditions are detected
by electronic sensors usually associated with
the driven component. One of the conditions is
that the platform must be on EITHER the second
or third deck (on a certain deck as opposed to
somewhere in between). If this condition is
sensed, the OR symbol will have an input, and
since only one input is needed, the OR symbol will
also have an output.
The other conditions to be met are that the
locking devices must be engaged and the access
doors must be shut. If the sensors are ener-
gized for these two Conditions, the AND symbol
Figure 4-19. A static logic panel for a cargo elevator.
77.290
will have the three inputs necessary to produce
an output. This output will then set up a starting
circuit allowing the motor to be started at your
final command.
The advantages of these electronic switches
over mechanical switches are low power con-
sumption, no moving parts, less maintenance,
quicker response, and less space requirement
A typical static logic panel found aboard sh
is shown in figure 4-19 a
Although there are logic symbols other tin
AND and OR, they all incorporate solid sta
devices. More information can be found in Ele<
trician's Mate 3 & 2, NAVEDTRA 10546-D.
68
CHAPTER 5
SHIPBOARD LIGHTING
The lighting aboard ship is one of the most
important systems and, many times, one of the
most neglected. Several factors contribute to
this seeming paradox maintenance in progress
on other systems, constant illumination in some
spaces, jury rigs, unauthorized changes, etc
Because of the continuous and unusual demands
on shipboard lighting systems, a vigorous program
of preventive and corrective maintenance must
be established and maintained. The most im-
portant feature of such a program is the protection
of personnel and equipment against electrical
hazards. We cannot stress enough: ALL SAFETY
PRECAUTIONS MUST BE CAREFULLY OB-
SERVED.
We shall discuss light sources that produce
general ambient illumination, as well as special
lighting applications. You will find more in-
formation on lighting systems and safety pre-
cautions in NAVSHIPS Technical Manual, chapter
9600; Electric Shock Its Cause and Its Pre-
vention, NAVSHIPS 250-660-42; and Lighting
on Naval Ships, NAVSEA 0964-000-2000.
LIGHT SOURCES
The primary purpose of a light source is
simply to produce light. The most common sources
of electric light used aboard naval ships are
the (1) incandescent, (2) fluorescent, and (3) glow
lamps. There is a complete listing of the lamps
used by the Navy in federal item '.dentification
number sequence in the Illustrated Shipboard
Shopping Guide (ISSG) FSC 6240. This listing is
carried aboard all ships and includes the elec-
trical characteristics, physical dimensions, and
an outlirte of each Navy type lamp.
INCANDESCENT LAMPS
Incandescent lamps produce light by means
of a tungsten or carbon filament which is heated
to incandescense by an electric current. Oxidation
with its attendant failure is prevented by sur-
rounding the filament with an inert gas or by
operating it in avacuuiru Most incandescent lamps
used for shipboard lighting are 115-120 volts,
25-200 watt, inside frosted, rough service (RS)
lamps. RS lamps (fig. 5-1) have specially con-
structed filaments supported at several points
to increase their ability to withstand shock.
The frosting conceals the filament and diffuses
the light emitted from the lamp. These lamps
may be used with or without reflecting equipment.
DESIGNATION
Standard incandescent lamps are designated
according to the (1) shape of bulb, (2) the finish
of bulb, (3) the type of base, and (4) the size
of the base.
BASE
BULB
(ENVELOPE)
STEM
LEAD-IN WIRE
SUPPORT
FILAMENT
12.359
Figure 5-1. Components of an incandescent lamp.
69
SHIPBOARD ELECTRICAL SYSTEMS
The shape of the bulb is identified by a
corresponding letter designation, as illustrated
in figure 5- 2 A. The designation letter is followed
by a numeral (not shown) that denotes the diameter
of the bulb in eighths of an inch.
The designation of lamps according to the type
of base is illustrated in figure 5-2B. The size
of the base is indicated by name mogul, candela-
bra, intermediate, etc. Each type of base is
provided in different sizes. The types are also
denoted by name bayonet, prefocus, bipost, etc.
Most lamps aboard ship are of the frosted
finish type to help eliminate the glare of the
filament.
CHARACTERISTICS
The average life of standard lamps for general
lighting service, when operated at rated voltage,
is 750 hours for some sizes and 1000 hours for
others. The light output, life, and electrical
characteristics of a lamp are materially affected
when it is operated at other than the design
voltage. Operating a lamp at less than rated
voltage will prolong the life of the lamp but
will decrease the light output. Conversely, oper-
ating a lamp at a higher than rated voltage will
shorten the life but will increase the light output.
Lamps should be operated as closely as possible
to their rated voltage.
FLUORESCENT LAMPS
Fluorescent lamps are now used for the
majority of lighting aboard naval ships. They
consume less power with greater illumination and
therefore are more efficient than incandescent
lamps.
Construction
The fluorescent lamp is an electric discharge
lamp that consists of an elongated tubular bulb
with an oxide- coated filament sealed into each
end to contain two electrodes. The bulb contains
a drop of mercury and a small amount of argon
gas. The inside surface of the bulb is coated
with a fluorescent phosphor. The lamp produces
invisible, shortwave (ultraviolet) radiation by
discharging current through the mercury vapor
in the bulb. The phosphor absorbs the invisible
radiant energy and reradiates it over a band
of wavelengths to which the eye is sensitive.
The Navy has standardized on three lamp
sizes: 8 watts, 15 watts, and 20 watts. The use
of fluorescent lamps of more than 20 watts
is limited to special installations.
Operation
Fluorescent lamps installed aboard ship art
of the hot-cathode, preheat starting type. 1
fluorescent lamp equipped with a glow-switc!
starter is illustrated in figure 5-3. The glow
starter is essentially a glow lamp containin|
neon or argon gas and two metallic electrodes,
One electrode has a fixed contact, and tta
other electrode is a U-shaped, bimetal strip
having a movable contact. These contacts art
normally open.
When the circuit switch is closed, theit
is practically no voltage drop across the ballast,
and the voltage across the starter (S) is suffi-
cient to produce a glow around the bimetallic
strip in the glow lamp. The heat from the glm
causes the bimetal strip to distort and touch
the fixed electrode. This action shorts out the
glow discharge and the bimetal strip starts to
cool as the starting circuit of the fluorescent
lamp is completed. The starting current flows
through the lamp filament in each end of the
fluorescent tube, causing the mercury to vaporize,
Current does not flow across the lamp between the
electrodes at this time because the path is
short circuited by the starter and because the
gas in the bulb is nonconducting when the elec-
trodes are cold. The preheating of the fluorescent
tube continues until the bimetal strip in the starter
cools sufficiently to open the starting circuit,
When the starting circuit opens, the decrease
of current in the ballast produces an induced
voltage across the lamp electrodes. The mag-
nitude of this voltage is sufficient to ionize the
mercury vapor and start the lamp. The resulting
glow discharge (arc) through the fluorescent
lamp produces a large amount of ultraviolet
radiation that impinges on the phosphor, causing
it to fluoresce and emit a relatively bright
light, During normal operation the voltage across
the fluorescent lamp is not sufficient to produce
a glow in the starter. Hence, the contacts remain
open and the starter consumes no energy.
Characteristics
As temperature increases above normal, the
efficiency of fluorescent lamps decreases slowly,
and as the temperature decreases below normal,
efficiency decreases very rapidly. Hence, the
fluorescent lamp is not satisfactory for locations
in which it will be subjected to wide variations
in temperature.
Chapter 5 SHIPBOARD LIGHTING
CONE (C)
GLOBULAR (G)
ARBITRARY (A)
PARABOLIC (PAR)
ALUMINIZED
REFLECTOR
PEAR SHAPED (P) PEAR SHAPE WITH REFLECTOR (R) STRAIGHT SIDE (S) TUBULAR (T)
STRAIGHT SIDE (PS)
A - SHAPE OF BULBS
SCREW BAYONET FLANGED BIPIN
(SINGLE CONTACT) (SINGLE CONTACT)
A (MINIATURE)
SCREW
C (INTERMEDIATE)
D (ADMEDIUM)
PREFOCUS
(SINGLE CONTACT) SCREW SKIRTED
BIPIN
(T-6-F LAMP)
BIPIN
(T-I2-F LAMP)
SCREW SCREW WITH BAYONET BAYONET INDEXING
SHORT NUB (SINGLE CONTACT) (DOUBLE CONTACT)
BAYONET PREFOCUSING COLLAR PREFOCUSING COLLAR BAYONET SKIRTED
(DOUBLE CONTACT) (SINGLE CONTACT) (DOUBLE CONTACT) (DOUBLE CONTACT)
B (CANDELABRA)
SCREW ' *" BIPIN
SCREW (THREE CONTACT) PREFOCUS (T-I7-F LAMP)
BIPOST
(T-20 LAMP)
F( MOGUL)
B - TYPE OF BASE
Figure 5-2. Classification of lamps.
12.79:80
SHIPBOARD ELECTRICAL SYSTEMS
GLOW
LAMP
GLOW
SWITCH
S
CIRCUIT
SWITCH
27.360
Figure 5-3. Glow-switch starter and fluorescent
lamp.
Fluorescent lamps should be operated at
voltage within 10% of their rated voltage. If
the lamps are operated at lower voltages, un-
certain starting may result, and if operated at
higher voltages, the ballast may overheat. Oper-
ation of the lamps at either lower or higher
voltages results in decreased lamp life. The
performance of fluorescent lamps depends to a
great extent on the characteristics of the ballast,
which determines the power delivered to the
lamp for a given line voltage.
The failure of a hot-cathode fluorescent lamp
usually results from loss of electron-emissive
material from the electrodes. This loss proceeds
gradually throughout the life of the lamp and is
accelerated by frequent starting. Blackening of
the ends of the bulb progresses gradually through-
out the life of the lamp.
GLOW LAMPS
Glow lamps are electric-discharge light
sources which are used as indicator or pilot
lights on various instruments, fuseholders, and
control panels (fig. 5-4). Since glow lamps have
a relatively low light output, they are used to
indicate the energizing of circuits or the operation
of electrical equipment in remote locations,
rather than for illumination. These lamps offer
the advantages of small size, ruggedness, long
life, low power consumption, and operation in
standard lighting circuits.
7.40
Figure 5-4. Fuse holder with glow lamp.
The glow lamp consists of two closely spac
metallic electrodes sealed in a glass bulb t
contains an inert gas. The color of the 11
emitted by the lamp depends on the gas. N(
gas produces an orange- red light, and arj
gas produces a blue light. The lamp must
operated in series with a cur rent- limiting dev
to stabilize the discharge. The current-limit
device consists of a high resistance that
sometimes contained in the lamp base.
The glow lamp produces light only when'
voltage exceeds a certain striking voltage,
the voltage is decreased below this value,
glow suddenly vanishes. When the lamp is opera
on alternating current, light is produced o:
during a portion of each half-cycle and b
electrodes are alternately surrounded with a glc
When the lamp is operated on direct curre
light is produced continuously, and only 1
negative electrode is surrounded with a glow. T]
characteristic makes it possible to use the gl
lamp as an indicator of both alternating curn
and direct current.
LIGHTING FIXTURES
A lighting fixture is a device that hous
the lighting source (lamp). It acts to prov:
72
Chapter 5 SHIPBOARD LIGHTING
satisfactory illumination while reducing glare
and affording protection to the lamp from mechan-
ical and battle damage. Lighting fixtures are
manufactured for incandescent (fig. 5-5A and B)
or fluorescent (fig. 5-5C and D).
Permanent fixtures (incandescent or fluo-
rescent) are permanently installed to provide
general illumination and such detail illumination
as may be required in specific locations. GEN-
ERAL ILLUMINATION is based on the light
intensity required for the performance of normal
routine duties, DETAIL ILLUMINATION is pro-
vided where the general illumination is inadequate
for the performance of specific tasks. Sources
include berth fixtures, desk lamps, and plotting
lamps*
Portable fixtures are provided for lighting
applications that cannot be served by permanently
installed fixtures. These units are energized by
means of portable cables that are plugged into
outlets in the ship's service wiring system and
include bedside lights, desk lights, floodlights
and extension lights.
TRANSFORMERS
An understanding of transformers will help
you follow the discussion on lighting systems.
A INCANDESCENT OVERHEAD
FIXTURE
B INCANDESCENT
BULKHEAD FIXTURE
C FLUORESCENT OVERHEAD
FIXTURE
D FLUORESCENT
DESK FIXTURE
Figure 5-5. Lighting fixtures.
77.38
SHIPBOARD ELECTRICAL SYSTEMS
Basically, transformers work on the same prin-
ciples as the a.c induction motor described in
chapter 4. That is, the primary winding (450
VAC) receives power from the ship's service
supply. The secondary winding (120 VAC) pro-
duces a voltage due to the expanding and collaps-
ing magnetic field of the primary. This induced
voltage in the secondary is lower than the primary
due to the winding turns ratio. This type trans-
former is called a step-down transformer because
of the lower voltage in the secondary. Similar to
the a.c. induction motor, there are no electrical
connections between the primary and secondary
windings.
LIGHTING SYSTEMS
The lighting distribution system in naval
vessels is designed for satisfactory illumination,
optimum operational economy, maximum con-
tinuity of service, and minimum vulnerability to
mechanical and battle damage. Most ships have
two sources of power supply for lighting fixtures.
Normal supply is from the ship's service bus.
A designated number of fixtures can also be
supplied from the emergency distribution system.
Additionally, there is a third lighting system
that consists of battery-powered, relay-operated,
hand lanterns.
The first two systems consist of feeders from
the ship's service or emergency power switch-
boards, switchgear groups, or load centers to
distribution panels or feeder distribution fuse
boxes, located at central distribution points
from which power is distributed .to the local
lighting circuits.
The ac. ship's service power feeders are
normally 450-volt, 3-phase, 60-hertz circuits.
The lighting supply circuits are 450 -volt, 3-phase,
60-hertz, 3-wire circuits supplied from the power
distribution system to 450/120-volt transformer
banks.
Three small transformers are used instead
of one large transformer because the loss of a
single composite unit would result in a total
loss of power. By using three separate trans-
formers, reliability is increased* In the event of
an enemy hit or failure of one of the bank of
three single-phase transformers (fig. 5-6), the
remaining two will still carry approximately
58 percent of the initial bank capacity. The line
236.3
Figure 5-6. Single-phase transformer.
current must be sufficiently reduced to sts
within the limits of the rated current of tt
two remaining transformers.
A typical vital lighting load has access 1
two switchboards (fig. 5-7). Selection of eithe
of these sources is automatic through an auto
matic bus transfer (ABT) switch. Additionally
the emergency switchboard has three powe
supplies that are independent of each othei
As a result of this arrangement, the vital lightin
load can be automatically supplied from severs
primary sources.
The system ;3hown in figure 5-7 operates a
follows. If an undervoltage condition develop
on switchboard 2SA, which is the normal suppl;
for ABT switch #1, the ABT switch will transfe:
the lighting load center panel to the emergenc;
lighting load center panel whose power sourc<
is emergency switchboard 2E.
Emergency switchboard 2E is energized eithe]
from its normal or alternate ship's service
supply feeders, or from the local emergencj
Chapter 5 SHIPBOARD LIGHTING
SSSWB 2SB
450/120 X
LIGHTING
LOAD
CENTER
PANEL
SS SWBD 2SA
SSSWBO 1SB
EMERGENCY c ^ ^
LIGHTING 4 ^0/J20
LOAD
CENTER
VL
BUS TIE
EMERGENCY
SWBD
2E
SSSWBO ISA
450/1 2O
HH
EMERGENCY
SWBO
IE
EMERGENCY
GENERATOR
2E
EMERGENCY
GENERATOR
IE
Figure 5-7. Typical lighting distribution system.
77.48(770)
generator. Transfer between these supplies is
automatic by three electrically operated circuit
breakers. The circuit breakers are electrically
and mechanically interlocked to prevent closing
of more than one breaker at a time. Normally,
the emergency switchboard is energized from one
of the two ship's service supplies. If voltage on
the normal ship's service supply bus drops to
300 volts, or below, the load automatically
transfers to the alternate supply if 400 volts
or above is available at that source. (If 400
volts or above is restored to the normal supply,
the load will automatically retransfer to the
normal supply.) If both ship's service supplies
fail completely or if their voltage drops to 300
volts, the transfer system will operate auto-
matically to start the emergency generator and
connect it to the emergency switchboard.
DARKENED SHIP
EQUIPMENT
Darkened ship is a security condition designed
to prevent the exposure of light, which could
reveal the location of the vessel. Darkened-ship
condition is achieved by means of (1) light traps
that prevent the escape of light from illuminated
spaces, or (2) door switches that automatically
disconnect the lights when the doors are opened.
A light trap is an arrangement of screens
placed inside access doors or hatches to prevent
the escape of direct or reflected light from
within (fig. 5-8). The inside surfaces of the
screens are painted flat black so that they will
reflect a minimum of light falling on them.
Light traps that are used to prevent the escape
75
SHIPBOARD ELECTRICAL SYSTEMS
P PAINT BLACK
TO HERE
Figure 5-8. Light trap.
77.46
of white light should have at least two black,
light-absorbing surfaces interposed between the
light source and the outboard openings. Light
traps are preferred to door switches in locations
where (1) exit and entrance are frequent; (2)
interruption of light would cause work stoppage
in large areas; (3) light might be exposed from
a series of hatches, one above the other on
successive deck levels; and (4) where many
small compartments and passages are joined
by numerous inside and outside doors that would
complicate a door- switch installation.
A door switch is mounted on the break side
of a door jamb (inside the compartment) and
operated by a stud welded to the door. When
the door is opened, the switch automatically
opens at the same time. Door switches are
connected in a variety of ways to suit the
arrangement of the compartment concerned.
All door switch installations are provided
with lock-in devices or short-circuiting switches
to change the settings of the door switches, as
required from lighted ship to darkened ship, and
vice versa.
RED ILLUMINATION
When a person leaves a well-lighted space and
enters a dimly lighted space, his vision is im-
paired until his eyes become accustomed to
the dark. When he can again see, his eyes are
said to be dark adapted. For personnel having
battle stations or watch stations topside, this time
interval could be detrimental to his ability to
stand his watch. The primary purpose of red
illumination is to provide low-level illumination
access routes to dimly lighted areas with minimum
interference to dark-adapted vision.
Red illumination is accomplished by using
standard red light fixtures or red filters over
standard white lights.
BLUE ILLUMINATION
A unique problem arises in the illumination
of spaces that contain radar system display
consoles. Normal lighting (standard white light)
excites the phosphor coating on the inside of the
cathode ray tube (CRT). This results in a dimming
of the target trace , thereby affecting the operator's
ability to see the target.
The conventional solution for years was to
darken the room. This improved the CRT display
but hindered other important ongoing operations
in the room, such as reading charts and messages,
plotting on status boards, and PMS requirements,
A solution to the problem was found by using
blue illumination. The basic principle of this
lighting system is frequency sharing. A broad
band of blue light is allocated for ambient
illumination, and the remaining portion of the
visible spectrum :.s used for CRT viewing. The
system is referred to as Broad Band Blue (BBB)
lighting.
White light contains all the colors of the
visible spectrum, therefore, any ambient illumi-
nation has some white light. By using two filters
we can almost eliminate the white light to the
CRT.
A blue filter is placed over the fluorescent
fixtures (fig. 5-9) which allows only the desired
wavelengths to pass, leaving enough ambient
illumination but decreasing the white available to
interfere with the CRT.
A second filter, amber, which will not pass
the wavelengths of the blue light but will allow
the CRT signal to foe seen, is placed over the
CRT.
The combination of blue and amber filters
provides improved scope visibility with an illumi-
nated working environment.
Chapter 5 SHIPBOARD LIGHTING
BBB FIXTURE-
WITH
DAYLIGHT
LAMPS
CRT SIGNAL PASSED
BY SCOPE
AMBER FILTER
BLUE FILTER
(TUBULAR)
BLUE LIGHT
REJECTED
BY SCOPE AMBER
Figure 5-9. BBB lighting system.
27.361
SPECIAL LIGHTING
APPLICATIONS
Up to this point we have limited our discussion
of shipboard lighting to general ambient illumi-
nation. In the next portion of this chapter we shall
describe different lights and fixtures not generally
associated with compartment illumination.
REPLENISHMENT-AT-
SEA RED LIGHTING
To enable extended periods of operations at
sea, units of the fleet receive the logistic support
they require by means of replenishment~at-sea
(RAS) operations.
In the past most RAS operations were conducted
during daylight hours because of visibility con-
siderations. With increased demands for night
operations the need for night RAS became increas-
ingly important. RAS lighting (fig. 5-10) permits
night replenishment with minimum risk to the
safety of both ships and personnel.
Hull Contour Lights
Hull contour lights (fig. 5-10) consist of
three red 25-watt lights shown by the control
(replenishment) ship during the approach and
while the receiving ship is alongside. These
lights are located at the fore and aft extremes
of that portion of the side parallel with the keel.
*&*,
TRUCK LIGHT (DIMMED) %
SHOWN ONLY DURING 1
APPROACH OF
RECEIVING SHIP
f *", TASK LIGHTS
, (SHOWN ONLY WHEN
> REQUIRED BY RULES
OF THE ROAD)
WAKE LIGHT
SHOWN ONLY DURING
APPROACH OF
RECEIVING SHIP
Figure 5-10. RAS lighting.
27.362
SHIPBOARD ELECTRICAL SYSTEMS
Obstruction Lights
The obstruction lights indicate to the control
hin items which may interfere with the cargo
^ 'it approaches the receiving ship, such as
de^k edges, missile launches, etc. Six one-cell,
-ed-lens, pin-on-type flashlights (fig. 5-11A) or
ix chemical lights (fig. 5-11B) are attached in
a straight line to a 6-inch wide, 12-foot long
of white canvas, which is placed along the
deck edge or along other obstructions outb
of the receiving ship.
Station Marker
Light Box
A portable light box (fig. 5-12) is loot
at the replenishment station of both the com
and approach ships. It uses a code (table E
to indicate the commodity toeing transfer:
Figure 5-11. One-cell flashlight and chemical light (obstruction lights).
Phone/Distance
Line Marking
The phone/distance line is hung between tt
two ships to indicate the distance between their,
and can be used to hold sound-powered telephone
cable. A single chemical light is attached at ever)
20-foot interval along the phone/ distance line, J
cluster of three chemical lights is interspersed
along the line at 60-, 100-, and 140 r foot intervals,
(See figure 5-13.)
Lights for Work Areas
To minimize danger to personnel, red flood-
lights provide illumination in working areas on
deck, in holds, and in cargo loading areas,
A typical configuration is shown in figure 5-14,
VISUAL LANDING
AIDS
Figure 5-12. -Station marking light
Visual landing aids (VLA) are lighting devices
and fixtures installed aboard nonaviation type
78
Chapter 5 SHIPBOARD LIGHTING
Table 5-1. Station marking light box code
COMMODITY
TRANSFERRED
MISSILES
AMMUNITION
FUEL OIL
DIESEL OIL
NAVY
DISTILLATE (ND)
AVGAS
JET FUEL
(JP-5)
WATER
STORES
PERSONNEL AND/
OR LIGHT FREIGHT
FUEL OIL AND
JP-5
ND AND JP-5
STATION
MARKER
LIGHT BOX
27.368
ships to aid helicopter pilots in all-weather
and night operations.
Primarily the VLA system consists of a
Stabilized Glide Slope Indicator (SGSI). The SGSI
projects a tri-colored beam of light (fig. 5-15)
centered along a safe glide path to the ship.
The upper sector of the light beam is green,
the center portion (command path) is amber,
and the lower section is red. In operation the
helicopter pilot flies into (acquires) the beam
and follows the command path to the ship. The
glide slope indicator is mounted on a stabilized
platform which compensates for the ship's roll
and pitch to keep the projected glide path steady.
Other fixtures (fig. 5-16) indicate to the
pilot the deck edge, the line-up position, the
touchdown point, and any unfavorable landing
condition. Various flood lights ilium "nate struc-
tures around the landing area for better depth
perception.
NAVIGATION AND
SIGNAL LIGHTS
Running, anchor, and signal lights include
all external lights used for navigational and
signaling purposes between ships to reduce the
possibility of collision and to transmit intelli-
gence. For design convenience, these lights
are divided into three groups as follows:
(1) Navigation Lights (as specified by the
International Rules of the Road) :
Masthead
Minesweeping
Range
Side-port
Side- starbo ar d
Stern (white)
Towing
Not-under-command (breakdown) and
man-overboard
Ship's task
Anchor-aft
Anchor-forward
(2) Signal Lights (Station or Operational):
Aircraft warning
Stern (blue)
Wake
Contour approach light (replenishment)
Polarity signal
Speed light (also used as aircraft warn-
ing or replenishment red truck lights)
Station keeping (mine sweeping)
Identification light for submarines
Station marking box (replenishment)
Revolving beam ASW light
(3) Signal Lights (Visual Communication):
Blinker
8-inch searchlight
12-inch searchlight (all types)
Infrared transmitters
Multipurpose signal light
SHIPBOARD ELECTRICAL SYSTEMS
USE A CLUSTER OF THREE CHEMICAL LIGHTS AT THE 60, 100 AND !40 FOOT
MARKERS. USE ONE LIGHT AT ALL OTHER MARKERS.
NOTE: PIN-ON ONE-CELL RED FLASHLIGHTS MAY BE USED
IN LIEU OF CHEMICAL LIGHTS.
CONTROL SHIP
MARLINE
1- CLASHING
RECEIVING SHIP
i$S#*TYPICAL INSTALLATION
Figure 5-13. Phone/distance line markings.
RAS LOW LEVEL (RED) FLOODLIGHTS
TO MARK AND LIGHT LANDING AREA
RAS LOW LEVEL (RED) FLOODLIGHTS
TO ILLUMINATE WORKING AREAS
STATION MARKING BOX
SYMBOL 285
OBSTRUCTION LIGHTS FOR DECK EDGE
OBSTRUCTION LIGHTS
FOR VERTICAL OBSTRUCTIONS
Figure 5-14. RAS work area lighting on receiving ships.
80
27.366
Chapter 5 SHIPBOARD LIGHTING
VERTICAL FIELD ANGLE
ANGLE OF
ELEVATION
FLIGHT
DECK
GSI
LIGHT
SOURCE
<L
GREEN
AMBER
RED
111.172
Figure 5-15. -Glide slope indicator and light beam.
Navigation Lights
The number location, arc, and range of
visibility of the navigation lights, which must
S displayed from sunset to sunrise by *n
ships in international waters, are established
Sy tie International Regulations "*"***"*
Collisions at Sea. Title tt, United States Code
Section 1051-1094, is the statutory law that
requires the Navy to comply with the Inter-
national Rules of the Road, or as allowed by an
exfstSg waiver to be issued covering the vessel
being built.
MASTHEAD LIGHTS. -The masthead light
(white) is a 20-point (225<) Alight ; located oj .fee
foremast or in the forward part of the ^vessel.
It is a spraytight fixture provided with a ^50-
watt, 2-fUament lamp and equipped with an
SHIPBOARD ELECTRICAL SYSTEMS
(RED OR WHITE;
DECK SURFACE
FLOODLIGHTS
(WHITE)
LINE UP LIGHTS
Figure 5-16 Typical VL A installation with night deck and hangar on 0-1 level, dual landing approach,
82
Chapter 5 SHIPBOARD LIGHTING
external shield to show an unbroken light over
an arc of the horizon of 20 points that is, from
dead ahead to 2 points abaft the beam on either
side.
MINESWEEPING. The minesweeping lights
(green) are three 32-point (360) lights arranged
in a triangle on the forward mast. These lights
are burned when mines are present to warn
other ships of danger 3000 feet astern and 1500
feet on the sides.
RANGE LIGHTS. The range light (white)
is a 20 -point (225) light located on the mainmast
or the fore part of the vessel and is a spray-
tight fixture provided with a 50-watt, 2-filament
lamp. The vertical distance of the range light
must be at least 15 feet higher than the mast-
head light, and the horizontal distance must be
greater than the vertical distance of the masthead
light.
PORT AND STARBOARD SIDE LIGHTS.
The port and starboard side lights are 10 -point
(112 1/2) lights (fig. 5-17) located on the re-
spective sides of the vessel, showing red to
port and green to starboard. The fixtures are
spraytight, each provided with a 100 -watt, 2-
filament lamp and equipped with an external
shield arranged to throw the light from dead
ahead to 2 points abaft the beam on the respec-
tive sides.
STERN LIGHT. The stern light (white) is
a 12-point (135) light located on the stern
of the vessel. It is a watertight fixture pro-
vided with a 50-watt, 2-filament lamp and equipped
with an external shield to show an unbroken
light over an arc of the horizon of 12 points
of the compass that is, from dead astern to
6 points on each side of the ship.
TOWING LIGHTS. The towing lights (white)
for ships not normally engaged in towing opera-
tions are 20-point (225) lights similar to the
previously described masthead and range lights.
They are portable fixtures, each equipped with
a type THOF-3 cable and plug connector for
energizing the lights from the nearest lighting
receptacle connector. When these lights are
used, they are located vertically (6 feet apart)
in the fore part of the vessel. These lights
can be permanently installed on ships whose
normal operations call for towing, e.g., fleet
tugs, salvage vessels, etc.
BREAKDOWN AND MAN-OVERBOARD
LIGHTS. The breakdown and man-overboard
lights (red) are 32-point (360) lights located 12
feet apart (vertically) and mounted on brackets
IDENTIFICATION
PLATE
DIAGONAL
SCREEN BASE
PLATE
FORE AND AFT
SCREEN
77.41
Figure 5-17. Side light.
83
SHIPBOARD ELECTRICAL SYSTEMS
* A oft of and to starboard of the mast
that extend aft of ana rmnsvisiwl
or structure. This arrange' O f azimuth.
a rotaS snapswitch (fitted with a crank
the signal and anchor light supply
JrfcSntrol panel. These lights are mounted and
in conjunction with the snap's task
lights.
SHIP'S TASK LIGHT. -The ship's task light
is an array consisting of three 32-point (360)
ghte, stepped out 45* aft and to starboard of
the mast, in a vertical line, one over the other,
so that the upper and lower lights are the same
distance from, and not less than 6 feet above or
below, the middle light and are visible all around
the horizon at a distance of at least 2 miles.
The upper and lower lights of this array are
red. The center light is clear white.
The ship's task lights are connected to the
Navigational Light Supply and Control Panel so
that:
(1) The two red lights will burn steadily
to indicate that the ship is Not-Under- Command;
or
(2) The two red lights will flash (by rotating
the switch (crank type) handle) to indicate that
a rnan-overboard condition exists; or
(3) The three lights will burn simultaneously
to indicate that the ship is either launching or
recovering aircraft or is engaged in replen-
ishment-at-sea operations and, by the nature
of her work, is unable to get out of the way of
approaching vessels. The switch for this appli-
cation is labeled c 'Ship's Task Lights."
FORWARD AND AFTER ANCHOR LIGHTS.
The forward and after anchor lights (white)
are 32-point (360) lights. The forward anchor
light is located near the bow of the vessel, and
the after anchor light is at the top of the flag-
staff. The fixtures are splashproof, each provided
with a 50-watt, 1-filament lamp. The anchor
lights are energized through individual on-off
rotary snap switches on the signal and anchor
light supply and control panel in the pilothouse.
SUPPLY CONTROL AND TELLTALE
PANEL. -The supply, control, and telltale panel
for the running lights is a nonwatertight, sheet
metal cabinet designed for bulkhead mounting;
(fig. 5-18). B
Figure 5-18. Supply, control, and telltale
This panel is provided to aid a ship in !
her running lights in operation as prei
by the rules for preventing collisions ;
It is installed in or near the pilothouse ant
an alarm whenever one of the running
(masthead, stern, range, and side lights)
or has had a failure of its primary filanii
is operating on its secondary filament*
A dimmer control panel is used to d
running lights when directed. This panel pi-
only one position for dimming. In the dim p<
the visibility of the range, masthead, side
and stern light is reduced to approximate!;
yards.
Signal Lights (Station
or Operational)
AIRCRAFT WARNING LIGHT. The at
warning lights (red) are 32-point (360)
84
Chapter 5 SHIPBOARD LIGHTING
(fig. 5-19A) installed at the truck of each mast
that extends more than 25 feet above the highest
point in the superstructure. Two aircraft warning
lights are installed if the light cannot be placed
so that it is visible from any location throughout
360 of azimuth. However, a separate aircraft
warning light is not required if a 32-point red
light is installed at the truck of a mast for
another purpose. The fixtures are spraytight
and equipped with multiple sockets provided
with 15-watt, 1-filament lamps (fig. 5-1 9 A).
If a single lamp fails, all of the lamps in the
cluster should be replaced.
SPEED LIGHTS. The speed lights are combi-
nation red (top) and white (bottom), 32-point
(360) lights (fig. 5-19B). They are located at
the truck (top) of the mainmast, except when
the height of the foremast is such that it inter-
feres with their visibility; in this case, they are
located at the truck of the foremast. Two speed
lights are installed if their light cannot be
placed so that they are visible throughout 360
of azimuth.
Speed lights are provided to indicate (by means
of a coded signal) the speed of the vessel to
ships in formation. In other words, they indicate
the order being transmitted over the engine order
system. The white light indicates ahead speeds,
and the red light indicates stopping and backing.
The fixture is spraytight and equipped with a
multiple socket (fig. 5-19B) provided with nine
15-watt, 1-filament lamps. Six lamps are used in
the top of the socket for the red light and three
in the bottom for the white light; each light is
energized from a separate circuit.
The controller for the speed lights is located
in the pilothouse and is energized through the
supply switch on the signal and anchor light
control and supply panel. The speed light system
operates automatically when the circuit control
switch is placed in the MOTOR PULSE position
and the signal (speed) selector switch is set in
the desired position. This action established con-
nections to the motor-driven pulsator to provide
the signals.
STERN LIGHT. The stern light (blue) is a
12-point (135^ light similar to the previously
described white stern light. The light is installed
near the stern on ships that are engaged in convoy
operations and is mounted to show an unbroken
arc of light from dead astern to six points on
each side of the ship.
FIXTURE
MULTIPLE
SOCKET
A B
AIRCRAFT WARNING LIGHT
RED
WHITE
D MULTIPLE
SOCKET
C FIXTURE
SPEED LIGHTS
77.44
Figure 5-19. Aircraft warning and speed lights.
WAKE LIGHT, The wake light (white) is
installed on the flagstaff or after part of the
ship to illuminate the wake and is mounted so
that no part of the ship is illuminated. The
fixture is spraytight and of tubular construction.
One end of the fixture is fitted with an internal
screen, having a 1-inch diameter hole provided
SHIPBOARD ELECTRICAL SYSTEMS
with a lens through which light is emitted from
a 100 -watt, 2-filament lamp. A suitable mounting
bracket is included for adjusting the position of
the light. Thus, the wake light puts a "target"
in the ship's wake.
SUBMARINE IDENTIFICATION LIGHT. The
submarine identification light is displayed solely
for identifying a craft on the surface as a sub-
marine. Its display does not change any of the
Rules of the Road nor confer any privilege on
the ship showing it. The light is an amber
rotating light producing 90 flashes per m:.nute,
visible all around the horizon, and located approxi-
mately 6 feet above the masthead light.
REVOLVING BEAM ASW LIGHT. The re-
volving beam ASW light (fig. 5-20) is displayed
for intership signaling during ASW operations and
is installed on all ships equipped to participate
in ASW operations. The light is positioned on
either the yardarm or mast platform where it
^
Figure 5-20. ASW revolving beacon.
27.367
can best be seen all around the horizon. Two red,
two green, and two amber lenses are provided
with each fixture. Colors to be used are determined
by operating forces.
Signal Lights (Visual Communication)
The signal lights for visual communication
include the blinker lights located on the yardarm
and the 8- and 12-inch searchlights.
BLINKER LIGHTS. The blinker lights (white)
are used in much the same manner as searchlights
for communication but, because of their location,
many ships can receive the message at the same
time. They are located, one port and one starboard,
outboard on the signal yardarm. The fixtures are
spraytight, each provided with two clusters of six
15- watt, 1 filament lamps. Cluster 41 may "be used
singly for normal use. Through switching, cluster
42 may be added to 41 to increase brilliance for
communication at greater distance, or 4 2 may be
selected alone if 1 fails. The lights are operated
from signal keys located on each side of the
signal bridge.
SEARCHLIGHTS. Naval searchlights are
used to project a narrow beam of light to illuminate
distant objects. They are also used for visual
signaling. To accomplish its purposes, the search-
light must have an intense, concentrated source
of light, a reflector that collects light from the
source (to direct it in a narrow beam) , and a
signal shutter (to interrupt the beam of light),
Searchlights are classified according to the
size of the reflector and the light source. The
8-inch searchlight has an incandescent light
source, and the 12-inch can have either an in-
candescent or an inert gas light source.
The 8-inch signaling searchlight utilizes an
incandescent sealed beam lamp. It is designed to
withstand high vibratory shock and extreme
humidity conditions and will operate equally well
in hot or cold climates.
This searchlight may be furnished for opera-
tion with either a 60-hertz, 115-volt transformer
to step the voltage down to 23 volts, or without
a transformer to operate on 115 volts using the
proper rated sealed beam unit. The same unit
is available for use on small craft from a 28-volt
power source.
The searchlight (fig. 5-21) consists of the
(1) base, (2) yoke, (3) housing, and (4) lamp.
The base is equipped with a rail clamp to secure
the searchlight to the rail. The yoke is swivel-
mounted on the base so that it can be trained
through 360. The housing provides an enclosure
86
Chapter 5 SHIPBOARD LIGHTING
CLAMP RING
BACKSHELL
HOUSING
SHUTTER
HOUSING
BRACKET
LAMP
BASE CD
RAIL CLAMP
77.62
Figure 5-21. 8 -inch 60 -hertz sealed -beam
searchlight.
Three filter assemblies (red, green, and
yellow) are provided and can be readily snapped
in place over the face of the searchlight. The
shutter vanes can be locked in the open position
for use as a spotlight.
The backshell housing provides an enclosure
for the 115/23-volt transformer.
The 12-inch incandescent searchlight is used
primarily for signaling and secondarily for illumi-
nation. The searchlight (fig. 5-22) is comprised
of (1) mounting bracket, (2) yoke, (3) drum, and
(4) lamp (not shown). The mounting bracket
permits the searchlight to be secured to a vertical
pipe or to a flat vertical surface. The yoke is
swi vel-m ounted on the bracket to allow the search-
light to be rotated continuously in train. The steel
drum provides housing for the lamp and is
trunnion-mounted on the yoke to allow it to be
elevated and depressed. Clamps are provided for
locking the searchlight in any position of train
and elevation,,
The SIGNALING SHUTTER is a venetian-blind
shutter mounted inside the drum behind the front
door. It is held in the closed position by two
springs and is manually opened by a lever
on either side of the drum. The parabolic metal
reflector is mounted on the inside of the rear
door.
for the lamp and is composed of a front and a
rear section. The front section comprises the
shutter housing, and the rear section comprises
the backshell housing. The two sections are held
together by a quick-release clamp ring that
permits easy replacement of the lamp. The
backshell and lamp assembly, when detached,
may be used as a portable searchlight. The entire
housing is mounted on brackets attached to the
shutter housing and is supported by the yoke
to allow the searchlight to be elevated or de-
pressed. Clamps are provided to secure the
searchlight in train and elevation.
The shutter housing (fig. 5-21) contains the
Venetian blind shutter, which is held closed by
springs and is manually opened by a lever on
either side of the housing. The front of the
shutter housing is sealed by the cover glass
and a gasket. The rear of the shutter housing
is enclosed by a gasket and adapter assembly.
The adapter assembly provides a locating seat
for the lamp and incorporates a hook and key
arrangement that aligns the backshell housing and
retains it in position while attaching the clamp
ring to hold the two sections together.
SHUTTER
LEVER
DRUM
YOKE
MOUNTING
BRACKET
77.58
Figure 5-22. 12-inch incandescent searchlight.
87
SHIPBOARD ELECTRICAL SYSTEMS
The LAMP is usually a 1000-watt, 117-volt
incandescent lamp having special concentrated
filaments that reduce the area of the light
beam. The lamp is mounted in a mogul bipost
socket. The socket is located in front of the
reflector and can be adjusted only slightly.
The lamp can be replaced through the rear
door of the searchlight.
The light source must be at the focus of the
reflector for minimum beam spread and maximum
intensity. Some types of 12-inch incandescent
searchlights are provided with focusing adjust-
ment screws. Other types can be adjusted by
loosening the screws that hold the lamp-socket
support plate in position. Move the entire socket
assembly toward or away from the reflector
until the beam has a minimum diameter at a
distance of 100 feet or more from the light, and
retighten the screws. When checking the diameter
of the beam, be sure the rear door is tightly
clamped shut.
A screen hood is provided for attachment
to the front door to limit the candle power of
the beam, to cut down its range, and to reduce
stray light, which causes secondary illumination
around the main beanie The hood also provides
for the use of colored filters.
The 12-inch mercury-xenon arc lamp (fig.
5-23) has a 1000-watt short-arc and requires
45 amperes to start and 18 amperes to operate.
It is supplied from the ship's 117-volt, 60-hertz,
single-phase power. The lamp consists of two
tungsten electrodes spaced approximately 1/4
inch apart inside a 2-inch diameter quartz
bulb. The bulb contains a small quantity of
liquid mercury and xenon gas at a pressure of
3 to 5 atmospheres when the lamp is cold (an
atmosphere at sea level is equivalent to 14.7
psi). After the arc is started and the lamp attains
a stable operating temperature, the internal
pressure increases to approximately 20 atmos-
pheres. The lamp does not produce full-light output
until this pressure is reached and all of the mer-
cury has been vaporized. The lamp differs from the
incandescent lamp in that it requires a high volt-
age, RF current for starting and a ballast for
operating at rated output. Because of the high
voltages involved and the high pressure of these
lamps, safety precaution should be observed.
The LAMP ADJUSTER ASSEMBLY is secured
to the top of the searchlight drum and extends in-
side the drum to provide a mounting for the
mercury-arc lamp. The assembly affords longi-
tudinal traverse (toward or away from the re-
flector), horizontal (from side to side), and
vertical adjustments of the lamp.
LOCK
SCREW
I AMP ADJUSTER
ASSEMBLY
FOCUSING
HAM OLE
REAR
DOOR
MERCURY-XEN
ARC LAMP
SHUTT
" LEVEi
REFLECTOR
71
Figure 5-23. 12-inch mercury-xenon searchli
The BALLAST UNIT, located out of
weather near the searchlight, consists of
transformer and five resistors enclosed ii
steel box. The unit provides the necess
ballast voltage in series with the lamp to ma
tain constant current for normal operation.
The STARTER UNIT, enclosed in a wat
tight box, is mounted in the lamp housing
consists of the necessary components for start
and operating the lamp. The electrical connect!
from the ballast unit to the starter unit
provided by a cable equipped with a waterti
Plug.
When the lamp is extinguished, whether
or cold, the internal resistance between electro
is so high that the arc will not restart w!
normal line voltage is applied. Hence, a spet
high- voltage, RF circuit is incorporated to pro^
instant starting, irrespective of whether the la
is cold or hot. However, the lamp is har
to start while it is hot and at maximum intei
pressure. The RF circuit is capable of produc
a voltage from 40,000 to 60,000 volts. After
arc is started, the lamp will operate on nori
voltage of 60 to 70 volts.
The ship's single-phase, 115-volt, 60-he
power is supplied to the ballast unit through
disconnect switch located adjacent to the sear
light.
88
Chapter 5 SHIPBOARD LIGHTING
INFRARED TRANSMITTERS. The infrared
transmitters (beacons) are designed to operate
in the infrared frequency spectrum. Because
infrared radiation is invisible, these transmitters
provide a means for signaling at night during
darkened- ship conditions. The beacons are located
on either side of the signal yardarm and may be
operated separately or simultaneously by either
of two manual keys. An infrared receiver is
used by the receiving ship to observe the signal
from the transmitting ship.
MULTIPURPOSE SIGNAL LIGHT. The port-
able multipurpose signal light (fig. 5-24) pro-
duces a high intensity beam of light suitable
for use as a spotlight or as a blinker (by means
of a trigger switch located on the rear handle)
for visual communications. The light is designed
to operate from an internal battery (three type
BA-2 dry cells connected in parallel), or from
the 120-volt a.c. ship's supply via a 120/20-volt
transformer mounted in the stowage box. The
front handle is adjustable to assure a steady
position for signaling, and front and rear sights
provide for holding the beam on the desired
target.
Supplied with the light, in addition to the
stowage box, are red, green, and yellow lenses,
a 15-foot power cable for supplying power from
the ship's a.c. source to the stowage box, a
25-foot cable for supplying power from the
FRONT SIGHT
LAMP RETAINING
RING
LAMP GASKET
SEALED-BEAM
LAMP
LATCH
HOUSING
FRONT
HANDLE
REAR
SIGHT
SPONGE
RUBBER
CUSHION
LAMP
SOCKET
SWITCH
PLATE
SWITCH
DPDT
REAR
HANDLE
ASSEMBLE
CONNECTOR
' FORWARD POSITION
101.5
Figure 5-24. Multipurpose signal light.
89
SHIPBOARD ELECTRICAL SYSTEMS
stowage box to the light, and the manufacturer's
technical manual.
Floodlights and Lanterns
FLOODLIGHTS. The floodlight (fig. 5-25A)
consists of a splashproof housing equipped with
a rain-shielded, hinged door secured with a
trunk type latch. The 300-watt lamp is the sealed-
team type. The lamp housing is trunnioned on
a yoke which in turn is mounted on a sho,
absorbing base. The light is secured in elevatt
by a clamp on the yoke. Train positioning
accomplished by friction within the shock t
sorbing base. Each floodlight is furnished witt
3-conductor cable (including a green lead to gron
the metal housing) for connection into the light!
circuit.
Larger 500 -watt floodlights (not shown), usi:
a mogul screw base lamp, are also widely use
FLOODLIGHT
HAND LANTERN
(MANUAL OPERATED)
PORTABLE FLOOD LANTERN
HAND LANTERN
( RELAY OPERATED)
Figure 5-25. Floodlights and lanterns.
90
77,*
Chapter 5 SHIPBOARD LIGHTING
Floodlights are installed on weather decks at
suitable locations to provide sufficient illumi-
nation for the operation of cranes and hoists, and
the handling of boats. New high-level illuminating
floodlights are being developed for evaluation by
Naval Sea Systems Command,,
Two types of dry battery lanterns are available
for installation in certain strategic locations to
prevent total darkness in case the lighting power
fails. One model is hand operated. The other is
operated automatically by a relay when the regular
power fails.
MANUALLY OPERATED HAND LANTERN.
The manually operated hand lantern (fig. 5-25B),
consists of a watertight plastic case containing
two (6-volt) batteries connected in parallel.
It includes a sealed beam lamp, rated at 5
volts, but operated at 6 volts (when the batteries
are new) to increase the light output. A rigid
handle is secured to the top of the case. The
lantern is operated by a toggle switch, the lever
of which is convenient to the thumb. When the
batteries are fresh, the lantern can be used
continuously for approximately 8 hours before
the light output ceases to be useful.
Manually operated lanterns are installed as
an emergency source of illumination in spaces
that are manned only occasionally. These lanterns
are also used in certain areas to supplement the
relay-operated lanterns.
Manually operated hand lanterns must not be
removed from the compartments in which they
are installed unless the compartments are to be
abandoned permanently.
RELAY-OPERATED HAND LANTERN. The
relay-operated hand lantern is similar to the
manually operated type except that the relay
housing is mounted topside of the lantern case
(fig. 5-25D) in place of the handle. The 115-volt
a.c. version is identified by symbol 101.2. Symbol
102.2 identifies the 115-volt d.c. type. A 3-con-
ductor cable (including a green conductor to ground
the relay metal frame) is provided for connection
into the lighting circuit, THE RELAY-CON-
TROLLED LANTERN MUST ALWAYS BE IN-
STALLED WITH THE RELAY UPPERMOST.
This specific arrangement of the relay prevents
a proven fire hazard, which would be caused
if the liquid electrolyte (formed from battery
exhaustion) drained into the (otherwise inverted)
relay housing.
Relay- controlled lanterns are assigned to
spaces which require practically continuous
illumination. These spaces include essential watch
stations, control rooms, machinery spaces, and
battle dressing stations. The lanterns must illumi-
nate the tops and bottoms of all ladders and
flush-mounted scuttles. They must also be
mounted so as to illuminate all gages at vital
watch stations. Operating personnel will depend
on these lanterns for illumination when bringing
the machinery back on the line in the event of
a casualty. These lanterns must not be installed
in magazine or powder-handling spaces in which
fixed or semifixed ammunition is handled, or in
any location in which explosion-proof equipment
is required.
The lantern relay is connected in the lighting
circuit (in the space in which the lantern is
installed) on the power supply side of the local
light switch that controls the lighting in the
space concerned. Thus, the relay is operated
and will restore, causing the lamp in the lantern
to be energized from its batteries only when
power failure occurs, but not when the lighting
circuit is deenergized by the light switch. If
the space is supplied with both emergency and
ship's service lights, the lantern relay is con-
nected to the emergency lighting circuit only.
PORTABLE FLOOD LANTERN. The port-
able flood lantern (fig. 5-25C) consists of a
sealed beam lamp enclosed in a built-in lamp
housing equipped with a toggle switch. The
lamp housing is adjustably mounted on a drip-
proof, acid-resistant case provided with two
windows in each end.
The case contains four Navy type BB-254/U
storage cells. Each cell contains a channeled
section in which a green, a white, or a red ball
denotes the state of charge of the cell through
a viewing window. When a cell is fully charged,
all three indicator balls float at the surface of
the electrolyte. The green ball sinks when approx-
imately 10% of the cell capacity has been dis-
charged; the white ball sinks when the cell is
50% discharged; and the red ball sinks when the
cell is 90% discharged.
The lamp is rated at 6 volts but is operated
at 8 volts to increase the light output. When
operated with fully charged batteries, the lantern
can be operated continuously for approximately
3 hours without being recharged. The batteries
should be recharged as soon as possible after
the green ball (10 percent discharged) has sunk
to the bottom. The lanterns should be checked
at least once a week to determine whether the
green indicator balls are floating. If they are not
floating, the battery should be charged at a rate
of 1 1/2 to 2 amperes until all indicator balls
91
SHIPBOARD ELECTRICAL SYSTEMS
are floating at the indicator line. If the battery
is completely discharged, it will require from
20 to 25 hours to recharge it. After the charging
voltage has remained constant at 10 volts for 1
hour, discontinue the charging.
When necessary, add pure distilled water
to keep the electrolyte level at the indicator
line marked on the front of the cell. Do not
add enough water to bring electrolyte level
above the line because overfilling nullifies the
nonspill feature of the battery and may cause
the electrolyte to spurt out through the vent
tube. However, if the electrolyte level is not
at the indicator line, the charge indicator balls
will not indicate correctly the state of charge
of the battery.
Portable flood lanterns are often referred
to as damage control lanterns because they are
used by damage control personnel to furnish
high intensity illumination for emergency repair
work or to illuminate inaccessible locations
below deck.
MAINTENANCE
The intensity of illumination produced by
lighting installation begins to depreciate at ft
time the system is placed into operation. Tt
greatest loss of light (up to 30%) can usual!
be attributed to dirt and oil on lamps an
fixtures. A regular program of fixture and lam
cleaning will improve illumination aboard yot
ship.
Burned out incandescent lamps may be dis
posed of at sea, but for security reasons,
must be remembered that incandescent lamps m
float and therefore must first be broken.
Fluorescent lamps contain mercury gas whic
is poisonous. Therefore, all fluorescent lamp
must be collected and turned into a shore-toast
control point for land disposal. NO FLUOE
ESCENT LAMPS SHALL BE DUMPED INT
ANY BODY OF WATER, INCLUDING OCEAN:
92
CHAPTER 6
DEGAUSSING
A steel-hulled ship is like a huge floating
magnet. Because of its magnetic field, the ship
can act as a triggering device for magnetically
sensitive mines. Degaussing concerns the methods
and techniques of reducing the effects of the ship's
magnetic field to minimize the possibility of
detection by magnetic mines and other magnetic
influence detection devices.
The earth's magnetic field has various
strengths throughout the earth's surface. The
sensor of a magnetic mine is set to the strength
of the earth's magnetic field at the mine's location.
Now, if any ferrous metal is introduced into
the earth's magnetic field near the mjne, the
magnetic field around the sensor will be distorted,
causing the mine to blow up.
A steel ship which has received no anti-
magnetic, or degaussing, treatment has a large
magnetic field surrounding its hull. As the ship
moves through the water, this field also moves
and adds to, or subtracts from, the earth's mag-
netic field causing it to bend or move. To a
magnetic mine beneath the ship, this moving
magnetic field (ship) appears as a change or
variation in the surrounding magnetic environ-
ment. Magnetic ordnance is highly sensitive
to variations in the earth's magnetic field. When
the ship is degaussed, its field is altered or
modified so the ordnance can detect little, if any,
magnetic disturbance as the ship passes.
EARTH'S MAGNETIC FIELD
The earth's magnetic field acts upon all
metal objects on or near the earth's surface.
Figure 6-1 shows the earth as a huge permanent
magnet, 6000 miles long, extended from the arctic
to the antarctic polar regions. Lines of force
from this magnet extend all over the earth's
surface, exerting a magnetic influence on all
POINT
EARTH'S FLUX LINES"
EARTHS GEOGRAPHIC
NORTH POLE
[EARTH'S GEOGRAPHIC
'SOUTH POLE
EARTH AS A MAGNET
27.104
Figure 6-l Earth's magnetic fieldo
ferrous materials that are on or near the surf ace *
Since many of these ferrous materials them selves
become magnetized, they distort the background
field into irregular eddies and areas of greatly
increased or decreased magnetic strength. Thus,
the lines of magnetic force at the earth's surface
do not run on straight, converging lines like the
meridians on a globe, but appear more like the
isobar lines on a weather map.
By convention, the external direction of the
magnetic field of a bar magnet is from the
north pole to the south pole. Lines of force for
the earth's field, however, leave the earth in the
southern hemisphere and reenter in the northern
hemisphere. Therefore, we must think of the
polar region in the arctic as the north-geographic,
south-magnetic pole, which describes the di-
rection of polarity used in the field of degaussing.
Note in figure 6-1 that the magnetic meridians
form closed loops, arching from the earth's
93
SHIPBOARD ELECTRICAL SYSTEMS
magnetic core to outer space and reentering the
earth in the opposite hemisphere. Since all lines
of magnetic force return to their points of
origin, they form closed magnetic circuits. An
idea of the size of the earth's magnetic field
is apparent when you notice that lines of force
at the polar regions seem to extend vertically
into space. The size Of the closed loops formed
by these lines of force is staggering to the
imagination. It is impossible to eliminate the
earth's field; however, the effects of the ship
on this field may be lessened. Degaussing limits
the ship's distortion of the earth's magnetic field,
and some highly developed techniques are used
in the process.
The strength and direction of the earth's field
at any point is a function of the strength of the
individual components. The angle of the field
with the horizontal, sometimes called the dip,
may be easily determined by a dip needle, a simple
compass needle held with the needle pivot axis
parallel to the earth's surface. Since a compass
needle always aligns itself parallel to the lines
of force of a magnetic field, the dip needle indi-
cates the angle of the earth's field to the hori-
zontal by aligning itself with the lines of force
entering or leaving the earth at that point. Both
direction and strength of the field may be deter-
mined by means of a mine search coil and flux-
measuring equipment.
Since the earth's field can be resolved into
two components, the horizontal (H) component
and the vertical (Z) component, the vector sum of
the H and Z components will define the magnitude
and the direction of the total field at any point
on the earth's surface. The force of the magnetic
flux can be resolved into a horizontal and a
vertical component as shown in figure 6-2.
Table 6-1 shows horizontal and vertical
component strength, and the resulting total field
strength and direction for several representative
geographical locations in the northern and the
southern hemispheres*, Note that the vertical
component may be assigned either a positive or
negative value because lines of force leave the
earth in the southern hemisphere and reenter
in the northern hemisphere. Therefore, the upward
field in the southern hemisphere is assigned
a negative value, and the downward field in
the northern hemisphere is assigned a positive
value. There are two areas of maximum vertical
intensity but opposite polarity the north and
south magnetic poles. The vertical intensity at
FLUX
LINE
H=R COS 6
S.
GEOGRAPHIC
N.
GEOGRAPHIC
H AND 2 COMPONENTS
27.104
Figure 6-2. Horizontal and vertical components
of earth's magnetic field.
the magnetic equator is zero since the entte
field is horizontal*.
SHIP'S MAGNETIC FIELD
The magnetic field of a ship is the re sultan
of the algebraic sum of the ship's permanen
magnetization and the ship's induced magnet-
ization. The ship's magnetic field may have an)
angle, with respect to the horizontal axis of to
ship, and any magnitude.
SHIP'S PERMANENT
MAGNETIZATION
The process of building a ship in the present
of the earth's magnetic field develops a certaii
amount of permanent magnetism in the ship
The magnitude of the permanent magnetizatio:
depends on the earth's magnetic field at theplac;
where the ship is built, the material of whic!
the ship is constructed, and the orientatia
of the ship at time of building with re spec
to the earth's field.
94
Chapter 6 DEGAUSSING
Table 6-1 . Measurements of the earth's magnetic field at selected locations
LOCATION
HORIZONTAL (H)
COMPONENT
VERTICAL (Z)
COMPONENT
TOTAL FIELD
STRENGTH
DIRECTION OF
TOTAL FIELD
North Pole (Magnetic)
+620
620
90 down
Fairbanks, Alaska
120
+560
570
78 down
Stockholm, Sweden
150
+460
490
70 down
London, England
190
+440
470
69 down
Washington, D.C.
180
+540
570
72 down
Tokyo, Japan
300
+340
460
50 down
Manila, Philippine Islands
390
+100
410
14 down
Equator (Magnetic)
410
410
horizontal
Rio de Janeiro, Brazil
230
-080
250
20 up
Capetown, South Africa
140
-280
320
64 up
Buenos Aires, Argentina
230
-140
260
30 up
Melbourne, Australia
230
-560
610
68 up
South Pole (Magnetic)
-720
720
90 up
NOTE-A11 measurements are approximate.
27.378
The ship's permanent magnetization can be
resolved into the (1) vertical permanent field
component and (2) the horizontal permanent
field component. The horizontal permanent field
component can be resolved into the longitudinal
permanent field component and the athwartship
permanent field component. The vertical, longi-
tudinal, and athwartship permanent field com-
ponents of the ship are virtually constant and
are not affected by changes in heading or magnetic
latitude.
SHIP'S INDUCED
MAGNETIZATION
Any piece of iron in a magnetic field will
have magnetism induced in it. Therefore a ship,
by its very existence in the earth's magnetic
field, has a certain amount of magnetism induced
in it The ship's induced magnetization depends
on the strength of the earth's magnetic field and
on the heading of the ship with respect to the
earth's field.
All ships that are fitted with shipboard de-
gaussing installations, and other ships that do
not require degaussing installations, are de-
permed. Deperming is essentially a large-scale
version of demagnetizing a watch. The purpose
is to reduce permanent magnetization and bring
all ships of the same class into a standard
condition so that the permanent magnetization,
which remains after deperming, is approximately
the same for all ships of that class.
Thie ship's induced magnetization, like the
ship's permanent magnetization, can be resolved
into the (1) vertical induced field component and
(2) the horizontal induced field component. The
horizontal induced field component is also com-
prised of the longitudinal induced field component
and the athwartship induced field component.
Table 6-1 shows the force of the earth's
field which causes magnetic induction on the ship.
Therefore, the magnitude of vertical induced
95
SHIPBOARD ELECTRICAL SYSTEMS
magnetization depends on the magnetic latitude.
Remember the vertical induced magnetization is
maximum at the magnetic poles and zero at the
magnetic equator.
The vertical induced magnetization is directed
downward whenever the ship is north of the
magnetic equator and upward whenever the ship
is south of the magnetic equator* Hence, the
vertical induced magnetization changes with mag-
netic latitude, and to some extent, when the
ship rolls or pitches. The vertical induced
magnetization does not change with heading be-
cause a change of heading does not change the
orientation of the ship with respect to the vertical
component of the earth's magnetic field,
The longitudinal induced magnetization
changes when either the magnetic latitude or the
heading changes and when the ship pitches. If a
ship is headed in a north-geographic direction,
the horizontal component of the earth's magnetic
field induces a north pole in the bow and a south
pole in the stern (fig. 6-3A). In other words, the
horizontal component of the earth's field induces
a longitudinal, or fore-and-aft, component of
magnetization. The stronger the horizontal com-
ponent of the earth's magnetic field, the greater
will be the longitudinal component of magnet-
ization. If the ship starts at the south magnetic
pole and steams toward the north magnetic
pole, the longitudinal component of induced mag-
netization starts at zero at the south magnetic
pole, increases to a maximum at the magnetic
equator, and decreases to zero at the north
magnetic pole. Hence, for a constant heading
the longitudinal component of induced magnet-
ization changes when the ship moves to a position
where the horizontal component of the earth's
magnetic field is different that is, when the
ship changes its magnetic latitude.
If at a given magnetic latitude the shij
changes headings from north to east, the longi-
tudinal component of induced magnetization wil
change from a maximum on the north headinj
to zero on the east heading. When the shi]
changes heading from east to south, the longitu-
dinal component increases from zero on the eas
heading to a maximum on the south heading
On southerly headings a north pole is induce
at the stern and a south pole at the bow, whic
is the reverse of the conditions on northerl
headings,, The longitudinal component of induce
magnetization also changes, to some exten
as the ship pitches.
The athwartship induced magnetizatic
changes whenever either the magnetic latitude c
the heading changes, and whenever the ship roll
or pitches. When a ship is on an east headinj
a north pole is induced on the port side and
south pole on the starboard side (fig. 6-3B
which is the athwartship component of indue*
magnetization. The magnitude of the athwart sh
magnetization depends on the strength of tl
horizontal component of the earth's magnet
field at that latitude. This component is maxima
1 NORTH
\ \ l GEOGRAPHIC
I NORTH I
GEOGRAPHIC
A. LONGITUDINAL MAGNETIZATION B, ATHWARTSHIP MAGNETIZATION
OF A SHIP. OF A SHIP.
Figure 6-3. Effect of the earth's magnetic field upon a ship.
27.105:
Chapter 6 DEGAUSSING
at the magnetic equator for a ship on an east- west
heading and zero at the magnetic poles for a
ship on a north-south headingo
MAGNETIC RANGES
AND RANGING
A magnetic range is a station equipped to
measure the magnetic field of ships which pass
over measuring equipment located at or near
the bottom of the channel in which the ships
travel. The magnetic range is more commonly
called a Degaussing Range or Degaussing Station.
A ship is said to be ' 'ranged* ' when its
magnetic field is measured at a magnetic range
Ranging has two classifications: calibration
ranging and check ranging.
CALIBRATION RANGING
Calibration ranging provides information for
degaussing charts, determines initial degaussing
coil current, and indicates whether changes or
modification to the ship's degaussing installation
are required.
CHECK RANGING
Check ranging determines the adequacy of
current settings and the performance of de-
gaussing equipment as well as personnel.
For accurate ranging the ship must pass
directly over the range at a constant speed and
heading. The degaussing coils must be set cor-
rectly in accordance with the values given in the
degaussing folder. For depth correction, the
range officer must be notified of coil settings
and of the ship's draft, forward and aft, to the
nearest 6 inches
DEGAUSSING FOLDER
The ship's Degaussing Folder is a record of
the degaussing installation in the ship The folder
contains (1) a description of the degaussing
installation, (2) a record of inspections, tests,
and repairs performed by repair activities, (3)
the values of all coil currents for the ship's
positions and headings, and (4) a record of the
degaussing range runs. The Degaussing Folder
is necessary to the operation of the degaussing
system and must be safeguarded against loss.
Generally, the Degaussing Folder is in the
possession of the navigator. The engineer officer
provides the navigator with the names of engi-
neering personnel who will require access to the
folder.
The Ship's Force Degaussing Maintenance
Record, NAVSHIPS 1009, is a record of the
maintenance performed on the degaussing system
by the ship's force. When completed, the forms
are inserted in the Degaussing Folder.
BASIC OPERATION OF
SHIPBOARD DEGAUSSING
A coil of wire with current passing through
it will produce a magnetic field whose polarity
and magnitude are dependent on the amount
and direction of current flow. A shipboard de-
gaussing installation consists of one or more
of these coils in specific locations aboard ship
and a means to control the magnitude and direction
of the current through the coils. Compass-
compensating equipment, consisting of compen-
sating coils and control boxes, are also installed
as a part of the degaussing system to compensate
for the deviation effect of the degaussing coils
on the ship's magnetic compasses
DEGAUSSING COILS
The distortion of the earth's field caused
by the ship's permanent magnetization (vertical,
longitudinal, and athwartship components) and
the ship's induced magnetization (vertical, longi-
tudinal, and athwartship components) is neutral-
ized by means of degaussing coils. The degaussing
coils are made with either single-conductor or
multiconductor cables. The coils must be ener-
gized by direct current, which is supplied from
120-volt or 240-voltd.c. ship's service generators
or from degaussing power supply equipment in-
stalled for the specific purpose of energizing
the degaussing coils.
The degaussing coils consist of coils of
cable wound on the ship, each having the correct
location and the required number of turns to
establish the required magnetic field strength
when energized by direct current of the proper
value and polarity. The coils will then produce
magnetic field components equal and opposite to
the components of the ship's field. Each coil
consists of the main loop and may have smaller
loops within the area covered by the main loop,
usually at the same level. The smaller loops
97
SHIPBOARD ELECTRICAL SYSTEMS
oppose localized peaks that occur in the ship's
magnetic field within the area covered by the
main loop. The resultant effect of the degaussing
coils, when the currents are properly set, re-
stores the earth's field to the undistorted condition
around the shipo
M Coil
The M or main coil (fig, 6-4A) encircles the
ship in a horizontal plane usually near the water-
line. The M coil counteracts the magnetic field
produced by the vertical permanent and the ver-
tical induced magnetization of the ship (fig 6-5) .
Hence, the M coil current must be changed
when the ship changes magnetic latitude in order
to keep the M coil field as nearly as possible
equal and opposite to the field produced by the
ship's vertical induced magnetization The per-
manent vertical magnetization of a ship remains
constant o
'M FIELD 1
v^
A
^__^^ ^ M COIL ^^^/
M COIL
Q_COIL OR QI
AND QP COILS
F-COIL, OR FI
AND FP COILS
L FIELD
B
F ANDQ COILS
'L FIELD
L COIL LOOPS
L COIL
FIELD
F and Q Coils
The F or forecastle coil (figo 6-4B) encirc]
the forward one-fourth to one-third of the si
and is usually just below the forecastle
other uppermost deck; whereas, the Q or quarte
deck coil encircles the after one-fourth to or
third of the ship and is usually just below 1
quarterdeck or other uppermost deck The
and Q coils counteract the magnetic field pi
duced by the ship's longitudinal permanent i
longitudinal induced magnetization The shg
of the magnetic field produced by the F anc
coils is somewhat different from the magne
field produced by the ship's longitudinal ma
netism, but, in general, the two fields are oppos
and directly below the bow and stern of the si
(figo 6-6). The F and Q coil currents mast
changed when the ship changes its course
magnetic latitude in order to keep the c
strengths at the proper values to counteract i
changes in the ship's longitudinal induced 1112
netization. Two adjustments are necessary, one
change the F coil current and the other to char
MAGNETIC FIELD
INDUCED BY VERTICAL MAGNETIZATION
OF SHIP
-M COIL
MAGNETIC FIELD
INDUCED WHEN M
COIL IS ENERGIZED WITH POSITIVE POLARITY
27.;
27.107 Figure 6-5. Effects of induced vertical magneti
Figure 6-4. Types of degaussing coils. and M coil magnetism.
98
Chapter 6 DEGAUSSING
LONGITUDINAL
FIELD OF SHIP
NORTH
27.370
'igure 6-6 . Longitudinal field of ship and neutral-
izing fields of F-Q coils.
he Q coil current. In many installations the
conductors of the F and Q coils are connected
o form two separate circuits designated as the
r I-QI coil and the FP-QP coil (fig. 6-4B).
The FI-QI coil counteracts the magnetic field
iroduced by the ship's longitudinal induced mag-
letization. The longitudinal induced magnetization
Changes when the ship changes heading or magnetic
atitude, and the FI-QI coil current must be
changed accordingly.
The FP-QP coil counteracts the magnetic
ield produced by the ship ' s longitudinal perm anent
nagnetization. The longitudinal permanent mag-
tetization does not change when the ship changes
Leading or magnetic latitude; therefore, no change
s needed in the strength of the FP-QP coil.
, Coil
The L or longitudinal coil (fig. 6-4C) consists
>f loops in vertical planes that are parallel to
he frames of the ship. The coil counteracts the
oagnetic field produced by the ship's longi-
udinal permanent and longitudinal induced mag-
tetization. The L coil is more difficult to install
han the F and Q coils or the FI-QI and FP-QP
soils, but provides better neutralization because
t more closely simulates the longitudinal mag-
Letization of the ship. The L coil is commonly
.sed in minesweeper vessels.
The longitudinal induced magnetization changes
/hen the ship changes heading or magnetic lat-
tude; therefore, the L coil current must be
hanged accordingly. Aboard a minesweeper, the
a coil current must even be changed as the
vessel pitches. Roll or pitch adjustments, or
both, are necessary on all the degaussing coils
aboard minesweepers.
A Coil
The A or athwartship coil (fig. 6-4D) consists
of loops in vertical fore-and-aft planes. The A
coil produces a magnetic field that will counter act
the magnetic field caused by the athwartship
perm .anent and athwartship induced m agnetization.
The athwartship induced magnetization changes
when the ship changes heading or magnetic
latitude; therefore, the A coil (current) must be
changed accordingly.
MANUAL DEGAUSSING
SYSTEMS
Degaussing installations, as previously stated,
consist of different combinations of degaussing
coils and manual or automatic degaussing equip-
ment to control the current in these coils. The
selected combination depends on the size and the
intended use of the particular ship.
The current in the A coil and in the FI-QI
or F and Q coils must be changed whenever
there are changes in the ship's heading or in
the magnetic latitude, or both. Current in the
coils is controlled manually in the older in-
stallations and automatically in all newer in-
stallations. Current in the M and FP-QP coils
remains essentially constant with the current
in the M coil changing only when the ship changes
zones and the current in the FP-QP coil changing
only as a result of calibration.
Degaussing installations that control the coil
currents manually are energized from constant
voltage d.c. generators or from variable voltage
motor-generators and are called rheostat and
motor-generator installations, respectively.
Reversing switches are used to change the
polarity of the coils, except when provision for
the change has been made in the design of the
rheostat of the constant voltage supply or in the
generator control of the variable voltage supply.
RHEOSTAT CONTROL
In a rheostat degaussing installation the power
for the degaussing coils is supplied by a constant-
voltage d.c. generator; the coil currents are
controlled by adjusting a rheostat connected
in series with the coil and power supply. An
installation using rheostats to control the M,
SHIPBOARD ELECTRICAL SYSTEMS
FI-QI, and FP-QP coil currents is illustrated
in figure 6-7. Some installations use manually
operated rheostats while others use motor-
operated rheostats. In the manual type, the
rheostat is adjusted locally at the degaussing
switchboard by turning the rheostat handle. In
the motor-operated type, the rheostat shaft is
turned by a motor which is controlled from a
remote station by a push button. Motor-operated
rheostats are equipped for manual operation
the event of an emergency .
MOTOR-GEN ERATOR
CONTROL
In a motor-generator degaussing installatj
the power for the degaussing coils is suppl
by a motor-generator; the coil currents \
REMOTE READING
AMMETERS
FI-QI COIL
ft REMOTE
T REVERSING
SWITCH
120 OR 240
VOLT D.C.
SUPPLY BUS
OP-COIL
POWER
SUPPLY
LEADS TO
COMPENSATING
CIRCUITRY (CCCJ,
77,
Figure 6-7. -Manual degaussing system with rheostat control.
100
Chapter 6 DEGAUSSING
controlled by adjusting a rheostat in the generator
field circuit to vary the output of the generator.
A single-line diagram of this type installation
is illustrated in figure 6-8. The rheostats in the
generator fields can be operated either manually
or by a motor to change the generator voltage
and thereby adjust the coil current to the desired
value.
POLARITY
The polarity of the degaussing coil currents
is of particular importance. If the polarity of
any of the degaussing coils is incorrect, the ship
may be in much greater danger from magnetic
mines than if no degaussing were installed. The
coils, instead of cancelling the magnetic field,
would be adding to it. The polarity of a coil
should be checked as to whether the pointer of
the ammeter for the coil is on the POSITIVE
(right) or NEGATIVE (left) side of the zero-center
ammeter. Also, the polarity of a coil can be
checked by observing whether the positive or
negative plate glows in the neon indicator light
for the coil. For positive polarity the right-hand
electrode glows, and for negative polarity the
left-hand electrode glows*
The direction of current (polarity) can also
be checked by a degaussing polarity indicator or
a small compass. The polarity indicator dial
AMMETER
INDICATOR LIGHT?
PUSH BUTTON
REMOTE CONTROL
PANEL
AMMETER
MOTOR STARTING PUSH BUTTON
RHEO. PUSH BUTTON
TRANSFER SWITCH
LOCAL CONTROL PANEL
MOTOR
T TO COMPASS
COMPENSATING
COILS
TO COMPASS
COMPENSATING
COILS
TO COMPASS
COMPENSATING
COILS
MOTOR
.-^-RHEOSTAT > DRIVEN
IN GEN. I RHEO.
FIELD
Figure 6-8.- M, F, and Q coil installation with motor-generator control.
101
77.182
SHIPBOARD ELECTRICAL SYSTEMS
is marked to denote the direction of current,,
When taking polarity readings with the indicator
or small compass, move the device toward the
degaussing coil until a good deflection is obtained,
and no closer. The needle in the indicator or
compass will reverse its magnetic polarity if
the device is held too closely to the coils. The
indicator or compass should be checked after
each test to ensure that the magnetic polarity of
the needle has not reversed.
CHANGING COIL
CURRENTS
The Degaussing Folder for each ship gives the
current needed for each coil at all positions on
the earth's surface and at all headings. One or
more of the coil currents must be changed when
one of the following conditions occurs:
1. When the ship passes from one Z zone
to another.
The vertical intensity (Z component) of the
earth's field, which is maximum at the magnetic
poles and zero at the magnetic equator, is divided
into a number of Z zones. The number of Z
zones will vary, depending on the amount of com-
pensation provided by the particular installation.
Degaussing Chart No. 1 (fig. 6-9) illustrates
the Z zones for the Atlantic and Indian Oceans.
The reverse side of this chart (not shown)
contains the same number of Z zones for the
Pacific Ocean. The coil settings are filled in
(lower left of chart) for the various zones
after the ship has been ranged.
2. When the ship passes from one H zone
to another.
3. When the ship's heading changes fron
one sector to another.
The entire range of headings from to 360
is divided into a number of sectors, each coverin;
a part of the whole range of courses.
The Degaussing Course Corrections Settinj
Diagram No. 1 for the FI-QI coil and Diagrac
No. 2 for the FI-QI and A coils are illustrate
respectively in figures 6-11 and 6-12.
The Degaussing Course Correction Setting
Table No. 1 for the F and Q coils and Table
No. 2 for the F, Q, and A coils are illustrated
respectively in figures 6-13 and 6-14.
None of the degaussing coil currents are
changed as long as the course remains in one
sector, that is, the Z zone and H zone remain
unchanged. The FP-QP coil current is NOT
changed when the ship's heading or the ship's
position changes. The following changes are
necessary when changing from one sector to
another or from one zone to another:
1. The M coil current must be changed when
the ship moves from one Z zone to another. The
M coil current is NOT changed when the ship
moves from one H zone to another or when the
heading changes from one sector to another,
2. The F, Q, FI-QI, L, and A coil currents
are not changed when the ship moves from one
Z zone to another, but must be changed when
the ship moves to a different H zone, or when
the heading changes to a different sector.
The horizontal intensity (H component) of the
earth's magnetic field, which is maximum at
the magnetic equator and zero at the magnetic
poles, is divided into a number of H zones.
Similar to the Z zones, the number of H zones
will vary, depending on the degree of compensation
provided by the degaussing system. Degaussing,
Chart No. 2 (fig. 6-10) illustrates the H zones
for the Atlantic and Indian Oceans and the reverse
side (not shown) contains the same number of H
zones for the Pacific Ocean.
AUTOMATIC DEGAUSSING
SYSTEMS
As we have discussed, current changes are
necessary to produce the correct strength of
magnetism at different headings. You can imagine
how very time consuming, with inescapable human
error, it would be if personnel had to make the
calculations for the current changes and take
102
Chapter 6 DEGAUSSING
tf<
iH
CO
SHIPBOARD ELECTRICAL SYSTEMS
104
Chapter 6 DEGAUSSING
DEGAUSSING
COURSE CORRECTION SETTING DIAGRAM No. 1
MANUAL OPERATION
FI-QI COIL
HEADINGS ARE MAGNETIC
N
SWITCH IN NORTH
POSITION
(CURRENT POSITIVE)
SWITCH IN EAST-WEST POSITION
(CURRENT OFF)
SWITCH IN SOUTH
POSITION
(CURRENT NEGATIVE)
THE CURRENT IN THE FI-QI COIL IS TURNED ON (POSITIVE) FOR NORTHERLY COURSES,
OFF FOR EASTERLY AND WESTERLY COURSES, AND REVERSED (NEGATIVE) FOR SOUTHERLY
COURSES BY MEANS OF A SWITCH ON THE BRIDGE OR IN THE CHART HOUSE.
WHEN THE SHIP IS ON A NORTHERLY HEADING SET THE CURRENT IN THE FI-QI COIL
AT THE VALUE SHOWN IN DEGAUSSING CHART NO. 2 MANUAL FOR THE LOCATION OF
THE SHIP AT THE TIME. WHEN THE COURSE IS SOUTHERLY THE CURRENT SHOULD BE THE
NEGATIVE OF THIS VALUE.
CHANGE THE CURRENT VALUE IF THE SHIP MOVES INTO A DIFFERENT ZONE.
IN EMERGENCY, WHEN COURSE CHANGES ARE TOO RAPID TO FOLLOW, SET SWITCH
IN EAST-WEST POSITION.
(Supersedes NAVWEPS 8950/46F)
MAVSHIPS 8950 /1UF (REV. 3-67)
DG NO. 12
69.16
Figure 6-11. Degaussing course correction setting diagram No. 1.
corrective action. To eliminate these disad-
vantages, a control system was designed to
utilize the primary course indicating equipment
already aboard ship, the gyrocompass, in con-
junction with the degaussing coils. This system
is the automatic degaussing system.
There are many types of automatic degaussing
systems but they all use the same basic concepts
of operation. We shall describe the SSM system
which differs from older systems by the manner
in which the current is controlled and sent to
the degaussing coils. The SSM uses solid state
105
SHIPBOARD ELECTRICAL SYSTEMS
WNW
290'
WSW
250
3.
DEGAUSSING
COURSE CORRECTION DIAGRAM NO. 2- A
MANUAL OPERATION
HEADINGS ARE MAGNETIC
FI-QI
COIL(S)
^COIL(S)
mi HID
SWITCH TO
POSITIVE CURRENT
(NORTH HEADING)
NNW
340
N
SWITCH TO CURRENT OFF
(EAST-WEST HEADING)
SWITCH TO
NEGATIVE CURRENT
(SOUTH HEADING)
n w
ESE
110
SWITCH
TO
NEGATIVE
CURRENT
(WEST
HEADING)
SWITCH
TO
CURRENT
OFF )
(NORTH-
SOUTH :
HEADING)
NNE
020
SWITCH
TO
POSITIVE
CURRENT
(EAST
HEADING)
ssw
S 200
DEGAUSSING COIL HEADING SWITCH MUST BE KEPT IN POSITION
CORRESPONDING TO MAGNETIC HEADING OF SHIP IN ORDER TO OBTAIN
PROPER CURRENT POLARITIES AND MAGNITUDES.
THE SETTINGS OR CURRENT VALUES ARE OBTAINED PROM DEGAUSSING
CHART NO. 2-S MANUAL. SWITCH POSITIONS REQUIRED DURING SET-UP
OF CURRENTS ARE:
FI-QI
_COIL(S), NORTH POSITION
_COIL(S), .EAST POSITION
IN EMERGENCY, WHEN COURSE CHANGES ARE TOO RAPID TO FOLLOW,
TURN COILS OFF TO WHICH THIS SWITCH APPLIES..
(Supersedes NAVVEPS 8950/46G)
NAVSHIPS 89 50 /l*6 (REV. 3-67)
DG NO. 13
Figure 6-12. Degaussing course correction setting diagram No. 2.
69.17C
devices rather than the magnetic amplifiers in
older types.
SSM AUTOMATIC
DEGAUSSING SYSTEM
The SSM automatic degaussing system controls
the current in four independent degaussing coils.
"*- system (fig. 6-15 and 6-16) is made up of the
,
degaussing switchboard, FI-QI coil power supply, power supply.
FP-QP coil power supply, A coil power supplj
]VI coil power supply, and a remote control unil
Degaussing Switchboard
The degaussing switchboard receives 450 VA(
from ship's power and generates a refereno
signal, proportional to the ship's position an
heading, which controls the output of each coi
106
Chapter 6 DEGAUSSING
DEGAUSSING
COURSE CORRECTION SETTING TABLE N2 I.
( F AND Q COILS )
MANUAL OPERATION
This Table is to be used in ALL regions.
INSTRUCTIONS FOR USE =
By rtfrtnc to Dtgouing Chart N02. 9<ct th circle diagrams btlow whtfb correspond to thr M zone for
th position of th chip . The actual ttttingt to b uMd or thin found in th oppropriot* count loctort.
M ZONE
.115
SETTINGS BELOW ARE IN AMPERES /AMPERE TURNS
HEADINGS ARE MAGNETIC
'Strike out whatever is not applicable.
NAME OF SHIP
uss
u. s.
PORT OF 1 SSUE
TfQM TWT PAPTTTTY
DATE
2 May 69
UDC* UrAor* r Av/Xijl.i.i'*
ctxc,o^
(Supersedes NAVWEPS 8950- 46D)
NAVSHIPS 8950/I^D (REV. 3-67)
DG NO. 10
Figure 6-13. Degaussing course correction setting table No. 1.
107
69.17D
SHIPBOARD ELECTRICAL SYSTEMS
DEGAUSSING
COURSE CORRECTION SETTING TABLE NO. 2
(F,Q, AND A COILS)
MANUAL OPERATION
NORTHERN
This Table is to be used ONLY when the ship is in the
Degaussing Chart No. 1. Separate Tables are provided for the other two regions.
_ region shown on
INSTRUCTIONS FOR USE:
By reference to Degaussing Chart No. 2 select the circle diagrams below which correspond to the H zone for the position of the ship.
The actual settings to be used are then found in the appropriate course sectors.
SETTINGS BELOW ARE IN AMPERES/AMPERE TURNS '
HEADINGS ARE MAGNETIC
,r<rrminTFnTh>^
FOR OTHER ZONES (OVER)
NAME OF SHIP
uss - -
NATION
U.S.
PORT OF ISSUE
USN DEG* FACILITY
DATE
2 May 1969
*?.&.Qrt
*Strike out whatever is not applicable.
(Supersedes NAVWEPS 8950/46E)
NAVSHIPS89SO/14E (REV. 3-67) (FRONT)
OG NO. 11 B-33548
Figure 6-1 4. Degaussing course correction setting table No, 2 (Front),
108
69.171
Chapter 6 DEGAUSSING
REMOTE
CONTROL ASSEMBLY
Figure 6-15. SSM Automatic Degaussing System.
27.371X
Manual Channels (M & FP-QP)
The manual channels, M and FP-QP, located
in the degaussing switchboard, generate a
reference signal by applying 24 VDC to the
induced magnitude potentiometer shown in
darkened line on figure 6-1 7 . The wiper arm
on the potentiometer is adjusted to obtain the
desired signal in accordance with the ship's
Degaussing Folder. The polarity is selected
by the position of the manually operated polarity
switch. Only the M coil channel is shown in figure
6-17.
Automatic Channels (A & FI-QI)
The two automatic channels, A and FI-QI, also
located in the degaussing switchboard, are identi-
cal with the exception of a permanent bias current
that can be applied to the A coil and not to the
FI-QI (fig. 6-18). The permanent bias current
109
SHIPBOARD ELECTRICAL SYSTEMS
110
Chapter 6 DEGAUSSING
DEGAUSSING SWITCHBOARD
27.373
Figure 6-17. Manual Channel (M coil).
compensates for the permanent athwart ship com-
ponent of the ship's magnetism* The settingof the
permanent bias is found in the ship's Degaussing
Folder.
When either or both of the automatic channels
are switched to the manual mode, the reference
signal, magnitude, and polarity are determined
by the setting of the heading switch.
Figure 6-19 shows the A coil only.* In the
automatic mode a signal is applied to the dif-
ferential transmitter synchro TDX, which modi-
fies the true heading signal. The magnetic
variation dial is manually operated to adjust
the magnetic heading signal in accordance with
the known magnetic variation for the particular
area in which the ship is operating. The mag-
netic signal is then applied to the synchro
111
SHIPBOARD ELECTRICAL SYSTEMS
DEGAUSSING SWITCHBOARD
Figure 6-18. Automatic channel, manual operation*
27.374
receiver TR, which will turn the magnetic heading
indicator and the resolver. The resolver breaks
the magnetic heading signal into two separate
signals, one representing the sine, the other
the cosine of the magnetic heading angle. The
sine signal is used for the A coil, the cosine
for the FI-QI coil. The automatic induced poten-
tiometer establishes the maximum level to be
operated in the automatic mode. Also fed into
the demodulator and output amplifier are the
permanent bias (for the "A" channel only)
and the H-zone setting. An error sensor also
compares the input and output signals to the
demodulator. Any difference will activate an
error signal light on the degaussing switchboard.
The four reference signals that are developed
by each coil channel are supplied to the corre-
sponding power supply.
Coil Power Supplies
The coil power supplies contain silicon con-
trolled rectifiers. You will find a discussion on
the workings of these devices helpful in under-
standing the operation of the power supplies.
An SCR is a semiconductor device which can
be gated (turned on) during any portion of the
112
Chapter 6 DEGAUSSING
DEGAUSSING SWITCHBOARD
MAGNETIC
HEADING
INDICATOR
27.375
Figure 6-19 . Automatic channel, automatic operation (A coil only).
positive half-cycle of an a.c. signaL Refer to
figure 6-20A If the gate pulse fires at the
start of the half-cycle, the SCR will continue
to conduct during the entire half-cycle. If the
gate pulse fires 90 later (fig. 6-20B), the SCR
will conduct on only half of the half-cycle. There-
fore, we can control the firing rate of the SCR's
by controlling the gate pulse and thereby control
the output with a small signal.
This concept is used in the SSM degaussing
coil power supplies. Please note in figure 6-21
that the signal developed by the channel in the
degaussing switchboard goes through an isolation
amplifier to electrically isolate it from the
switchboard and the other three coil power
supplies. The signal then goes to a regulator
which also receives a current feedback signal
from the coil. The signals are compared and
then sent to the firing logic circuits. The firing
logic circuits control the basic firing angle
for the SCR's to control the output current An
error sensor compares the input and output
signals in the same manner as the error sensor
in the degaussing switchboard.
Two other types of automatic degaussing
systems installed aboard ships are the GM-1A
and the SM-9A. The basic principles of operation
SHIPBOARD ELECTRICAL SYSTEMS
PHASE DELAY
MAX OUTPUT
GATE PULSE
PHASE DELAY 90
HALFMAX OUTPUT
CONDUCTION ANGLE
27.376
Figure 6-20. Operation of silicon control rectifier.
are the same as for the SSM, therefore, we si
give only a brief description of the two systei
GM-1A AUTOMATIC
DEGAUSSING SYSTEM
The GM-1A automatic degaussing syst
consists of nine units; a degaussing switchboa
an automatic control unit (installed in the swit
board), a degaussing remote control panel, 1
rectifier power supplies (M coil and FP-
coil power supplies), two motor-generator s
(FI-QI coil and A coil), and two magnetic c<
trollers which are used only with the A c
and FI-QI respectively. As illustrated in figi
6-22, the FP-QP coil power supply may
either of two sizes, 3kWor 5kW, having diffen
DEGAUSSING
SWITCHBOARD
SILICON
CONTROLLED
RECTIFIER
ASSEMBLY
450V AC 30 60Hz
Figure 6-21, Coil power supply.
114
27.37?
Chapter 6 DEGAUSSING
1
O
8
I
LJ
r
GC
I
1:
S,
o: -3
P
00
CO
S
t
o
T3
o
o
o
=3
S
I
<M
CD
o:
o
QC
Ltl^.
p
O
I
115
SHIPBOARD ELECTRICAL SYSTEMS
-. ._.* *mw -. f - -- ___. >..- j_ jt. X^A V/WJL.LO iJLA V^ClDv? bill
paving different output ratings. automatic equipment fails, the FI-QI and the 1
T.^^ Systeiri provides automatic degaussing coil can also be controlled manually (Em er gene 1
rents for the FT-OT coil and the A coiL Manual^ '
AIIT. *
currents for the FI-QI coil and the A coil,
450 VOLT 60 Hz
3 PHASE POWER
12O VOLT 400 Hz
POWER
GYRO SIGNAL
F.l'QI DEGAUSSING COIL
FP-QP
POWER
SUPPLY
FP-QP DEGAUSSING COIL
FP-Q.p FI.ELD
FI-QI FIELD
Figure 6-23. -Type SM-9A automatic degaussing control system.
77.32'i
Chapter 6 DEGAUSSING
SM-9A AUTOMATIC
DEGAUSSING SYSTEM
The SM-9A automatic degaussing control sys-
tem comprises a degaussing switchboard (fig.
6-23), a remote switchboard, and FI-QI coil power
supply, an FP-QP coil power supply, and an M
coil power supply*
Degaussing Switchboard
The degaussing switchboard (fig. 6-24) con-
tains the controls required to operate the de-
gaussing system o The FI-QI control panel mounted
at the top of the switchboard contains all the
circuits required to control the FI-QI degaussing
currents in both the manual and automatic
modes of operation. The M control panel mounted
in the center left section of the switchboard
contains the controls and circuitry required
to control the M coil current. The FP-QP
control panel mounted center right contains
the controls for setting the FP-QP coil current.
At the bottom is located the power supply over-
heating alarm circuits and ground fault detector.
The remote control unit has three meters
which indicate the current in each of the three
degaussing coils. Three red lights mounted on
the unit indicate whether there is trouble in any
of the three circuits. One white light indicates
that the system is in manual operation, and
another indicates that the FI-QI current is
being controlled at the remote control unit by
the manual control switch on the remote unit.
The three power supplies contain the circuits
necessary to supply the currents to degauss
the ship. The only externally mounted -com-
ponents on the power supplies are indicator type
fuses which fuse the power circuits in the supplies.
LOCAL
CONTROL
UNIT
M
CONTROL
PANEL
FP-QP
CONTROL
PANEL
GROUND FAULT
DETECTOR PANEL
111.121
Figure 6-24. Degaussing switchboard.
117
CHAPTER 7
AUXILIARY SHIPBOARD EQUIPMENT
Personnel assigned to the electrical divi-
sion(s) maintain a variety of auxiliary equipment.
Much of this equipment is vital to the ship's
operation, and muoh of it is very complex in
nature. In this chapter we shall discuss the basic
operating principles of some of this equipment.
BATTERIES
Many types of equipment aboard ship utilize
batteries as their source of direct current
electricity. Such equipment includes portable
announcing equipment, portable and emergency
lighting equipment, ship's boats, dial telephone
systems, gyrocompass systems, and many others.
In some instances batteries are used as the only
source of power, while in others, they are used
as a secondary or standby power source.
A battery consists of one or more cells con-
nected together to function as a source of elec-
trical power.
PRIMARY CELL
A primary, cell consists of two dissimilar
materials (electrodes) immersed in acid. As a
broad definition, a primary cell is one in which
the chemical action eats away one of the elec-
trodes, usually the negative. When this happens,
the electrode must usually be replaced or the
cell must be discarded. The dry cells employed
in flashlights are common examples of primary
cells.
SECONDARY CELL
Generally, a secondary cell is one in which
the electrodes and the electrolyte are altered
by the chemical action that takes place when
the cell delivers current. These cells may be
restored to their original condition by forcing
an electric current through them in the direction
opposite to that of discharge. The automobile
storage battery is a common example ol
secondary cell.
Cells are connected together to provide
amount of voltage and current required of
battery. As an example, the common l2-\
automobile battery consists of 6 cells, &
cell producing approximately 2 volts.
TYPES OF BATTERIES
There are many different types of batteri
in use today, however, most of them are us
in special applications and are not commor
found in shipboard electrical equipment.
The dry cell, lead-acid and nickel- cadmiu
batteries are toy far the most common types
use aboard ship today. The material present!
in this chapter, though not all inclusive, pr<
vides the reader with a general view of the*
various types of batteries.
Dry Cell
The common carbon- zinc dry cell batter]
so-called because its electrolyte is not in
liquid state, is used in flashlights and battl
lanterns. Actually, the electrolyte is a rnois
paste. If it should become dry, it could m
longer transform chemical energy to electrica
energy. The name dry cell, therefore, is no
strictly technically correct.
CONSTRUCTION OF THE DRY CELL, Tto
construction of a common type dry cell is showi
in figure 7-1. The internal parts of the cell
are located in a cylindrical zinc container which
also serves as the negative electrode of the
cell. A carbon electrode is located in the center
and serves as the positive terminal of the
cell. The paste electrolyte is a mixture oi
several substances. Its composition may vary,
depending on its intended use and manufacturer,
118
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
POSITIVE
TERMINAL
STEEL
COVER
NEGATIVE
TERMINAL
EXPANSION
CHAMBER
PASTE
ELECTROLYTE
ZINC CAN
(NEGATIVE
ELECTRODE)
ASPHALT
SATURATED
PAPER GASKET
ASPHALT
SATURATED
INSULATING
WASHER
(4-) CARBON
ELECTRODE
PASTE COATED
PULPBOARD
SEPARATOR
CHIPBOARD
JACKET
236.28
Figure 7-1. Cutaway view of a dry cell.
Binding posts are attached to the electrodes
so that wires may be conveniently connected
to the cell.
CHEMICAL ACTION OF THE DRY CELL.
The action of the electrolyte on the carbon and
zinc electrodes of the dry cell produces an
electrical current flow when the cell is con-
nected to a load. In the process of producing
the electrical current, the chemical action eats
away the zinc container (negative electrode). In
the process of being discharged, it is common
for the zinc container to be sufficiently eaten
away that the electrolyte will leak from the cell.
The electrolyte is corrosive and will destroy
the internal parts of electrical or electronic
equipment with which it comes in contact.
To prevent damage to electrical equipment
from leaking electrolyte, dry cells should be
replaced immediately after they have been dis-
charged beyond their usable service life.
119
SHIPBOARD ELECTRICAL SYSTEMS
Battery-powered equipment should NEVER
be placed in stowage until the dry cells have
been removed.
SHELF LIFE OF THE DRY CELL. A cell
that is not being used (on the shelf) will gradually
deteriorate because of slow internal chemical
actions (local action) and changes in moisture
content. However, this deterioration is usually
very slow if cells are properly stored. High-
grade cells of the larger sizes should have a
shelf life of 1 year or more. Smaller size
cells have a proportionately shorter shelf life,
ranging down to a few months for the very
small sizes. If unused cells are stored in a
cool place, their shelf life will be greatly in-
creased; therefore, to minimize deterioration,
unused cells should be stored in refrigerated
spaces (10 to 35 F) that are not dehumidified.
Secondary (Wet) Cells
Secondary cells function on the same basic
chemical principles as primary cells. They
differ mainly in that they may be recharged,
whereas the primary cell is not normally a
charged. Some of the materials of a prima
cell are usually consumed in the process <
changing chemical energy to electrical euerg
In the secondary cell, the chemical reaction thi
produces the electricity does not consume tt
electrodes, but it does usually change the chemici
composition of the electrodes. Discharged sec
ondary cells may be restored (charged) to the!
original state by forcing an electric currei
from some other source through the cell i
the direction opposite that of discharge.
There are many different types of secondai
cells. Of these types, the lead-acid is the moi
widely used.
LEAD-ACID BATTERY. A lead- acid battei
consists of a number of lead-acid cells connectc
together, the number depending upon the voltag
desired. Each cell produces approximately
volts.
A lead-acid battery (fig. 7-2) consists of
hard rubber, plastic, or bituminous materi*
compartment into which is placed the cell elernenl
consisting of the positive and negative lead plates
The plates are insulated from each other I
CELL CONNECTOR
FILLER OPENING
IN CELL COVER
VENT PLUG
TERMINAL POST
TERMINAL CONNECTOR
CASE
RIB
236.3-
Figure 7-2. Lead- acid battery.
120
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
suitable separators (usually made of porous
plastic, rubber, or glass) and submerged in a
strong sulfuric acid solution (electrolyte).
Many batteries are assembled in a one-piece
container with compartments provided for each
cell. The cells are covered with the same
material as the battery container. Openings are
provided in the covers for the terminals and
the vent plug.
The terminals of a lead- acid battery are
normally distinguishable from one another by
their physical size and by the markings of the
manufacturer. The positive terminal, marked + f
is slightly larger than the negative terminal,
marked -. In addition, the terminals are some-
times color coded red for the positive terminal
and black for the negative terminal.
Vent plugs are of various designs to permit
the escape of gases that form within the cells
while preventing leakage or loss of the electro-
lyte.
It is important that the openings of the vent
plugs do not become clogged with dried elec-
trolyte and dirt. If this should happen, pressure
sufficient to burst the battery case could build
up inside the cells while they are being charged.
Lead- Acid Battery Operation. The active
materials in a charged lead- acid battery are
lead peroxide (the positive plate) and sponge
lead (the negative plate). The electrolyte is a
mixture of sulfuric acid and water. The strength
(acidity) of the electrolyte is measured in terms
of its specific gravity. Specific gravity is the
ratio of the weight of a given volume of electro-
lyte to an equal volume of pure water.
As the battery discharges, the acid in contact
with the plates separates from the electrolyte
and forms a chemical combination with the active
material of the plates changing them to lead
sulfate. Thus, as the discharge continues, lead
sulfate forms on the plates, and more acid is
taken from the electrolyte. The water content of
the electrolyte becomes progressively higher;
that is, the ratio of water to acid increases.
As a result, the specific gravity of the electrolyte
will gradually decrease during discharge.
If the discharged cell is properly connected
to a direct-current charging source (the voltage
of which is slightly higher than that of the cell) ,
current will flow through the cell in the direction
opposite that of discharge, and the cell is said
to be charging. The effect of the current changes
the lead sulfate on both the positive and negative
plates back to the original active form of lead
peroxide and sponge lead, respectively. At the
same time the sulfate is restored to the elec-
trolyte, thereby increasing the specific gravity
of the electrolyte. When all the sulfate has been
restored to the electrolyte, the specific gravity
will be maximum. The cell is then fully charged
and is ready to be discharged again.
During the battery charging operation quan-
tities of hydrogen and oxygen gases are generated
within the cell. If these gases are not vented,
the cell container may burst; therefore, the
gases must be vented to the atmosphere through
the vent plugs.
A mixture of hydrogen and air can be danger-
ously explosive. No smoking, electric sparks,
or open flames should be permitted near charging
batteries.
If a lead-acid cell or battery is allowed to
remain in a discharged condition for more than
24 hours, the lead sulfate on the plates hardens
and it becomes increasingly difficult for the
charging action to restore it back to the elec-
trolyte. If allowed to remain in a discharged
state for an excessive period of time, the cell
cannot be restored to its original charged con-
dition. Lead-acid cells should be maintained as
near a fully charged condition as possible.
You should also remember that sulfuric acid
added to a discharged lead-acid cell will NOT
recharge the cell and, in fact, can damage the
cell. Added acid only increases the specific
gravity of the electrolyte; it does not convert
the lead sulfate on the plates back into active
material (sponge lead and lead peroxide) and,
consequently, does not bring the cell back to a
charged condition. A charging current must be
passed through the cell to do this.
Only pure water should be added to a cell
to maintain the electrolyte at the proper level.
Specific Gravity. As the lead-acid cell dis-
charges, the plates convert to lead sulfate, the
sulfuric acid concentration in the electrolyte
becomes weaker, and the specific gravity of
the electrolyte approaches that of water (1.000).
A hydrometer (fig. 7-3) is used to measure
the specific gravity of the electrolyte, thereby
determining the charge/discharge state of a
lead-acid cell. The electrolyte of the cell being
checked is drawn up into the glass tube by means
of the rubber bulb at the top. The specific
gravity of the electrolyte is read from the
calibrated scale, which lies axially along the
body of the float.
There are several factors that may cause
inaccuracies in hydrometer readings. The spe-
cific gravity of the electrolyte is affected by
121
SHIPBOARD ELECTRICAL SYSTEMS
1150
DISCHARGED
Figure 7-3. Hydrometer.
236.39
its temperature. When heated, the electrolyte
expands, becoming less dense and its specific
gravity reading is lowered. Conversely, when
cooled, the electrolyte contracts, becoming
denser and its specific gravity reading is raised.
Thus, effects of temperature will distort the
readings.
When a reading is taken, the electrolyte in
a cell should be at the normal level. If the level
is below normal, sufficient fluid cannot be drawn
into the tube to cause the float to rise. Ii:
level is above normal, there is too much wait
the electrolyte is weakened, and the read
will be too low.
A hydrometer reading is inaccurate if tali
immediately after water has been added, becaii
the water tends to remain at the top of the eel
When water is added, the battery should be charge
for at least 1 hour to mix the water with ti
electrolyte before a hydrometer reading is take
CAUTION: Hydrometers should be flush
daily with freshwater to prevent inaccurate rea;
ings. Lead- acid battery hydrometers must!
be used for any other purpose.
Battery Capacity. Batteries are rated i
their ampere-hour capacity at a definite us
of discharge. Most Navy portable lead-acid IE
teries, except those used in aircraft, are rats
at a 10-hour discharge rate. The capacity t
the battery, then, varies with how it is discharge
in relation to its rated discharge rate. For ei
ample: Suppose a battery is rated at 200 ampeit
hours (will supply 20 amperes constantly to
load for 10 hours),, As shown in the table belo*
if it is discharged in less than 10 hours, it vS
deliver less than its rated ampere-hour capacit)
Discharge time
1 hour
2 hours
3 hours
6 hours
10 hours
Percentage of
ampere-hour
capacity delivered
55%
65%
75%
90%
100%
Types of Lead- Acid Battery Charges, -I
general, battery charges are used to initial!
activate a battery or to restore a battery to ife
charged state. The following types of charge
may be given to a lead-acid battery, depended
on the condition of the battery and PMS require-
ments:
1. Initial charge
2 Normal charge
3. Equalizing charge
4. Float charge
5. Emergency charge
When a new battery is shipped dry, ft
plates are in an uncharged condition. After flif
electrolyte has been added, the battery is give:
a long, low- rate, initial charge to convert tfe
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
plates into the charged condition. The charge is
given in accordance with the manufacturer's in-
structions, which are shipped with each battery.
If the manufacturer's instructions are not avail-
able, the charge should be made in accordance
with detailed instructions in current directives.
A normal charge is a routine charge, given
in accordance with the nameplate data during
the ordinary cycle of operation, to restore the
battery to its charged condition.
An equalizing charge is an extended normal
charge, given periodically to ensure that all
the sulfate is driven from the plates and to
restore the electrolyte to its maximum specific
gravity.
The floating charge is used to maintain a
battery at its fully charged condition. In this
type of charge, the battery is connected to a
charging voltage that is slightly higher than
the battery voltage, and the battery is charged
.constantly. The floating charge is usually used
on batteries that are used as standby power
sources for equipment such as dial telephones
or gyrocompasses.
The emergency charge is used when a battery
must be recharged in the shortest possible time.
The charge starts at a much higher rate than
is normally used and should be used only in an
emergency because this type charge may be
harmful to the battery.
Normally, the rate at which Navy lead-acid
batteries are charged is given on the battery
nameplate. If the available charging equipment
does not have the desired charging rates, the
nearest available rates should be used. However,
the rate should never be so high that violent
gassing occurs. NEVER ALLOW THE TEM-
PERATURE OF THE ELECTROLYTE IN ANY
CELL TO RISE ABOVE 125 F.
NICKEL-CADMIUM BATTERIES. Nickel-
cadmium batteries are made in both wet and
dry cell forms. Both forms are used in appli-
cations where lead-acid and conventional dry
cell batteries are employed.
Nickel-cadmium cells are generally superior
to lead- acid or dry cells:
1. In dry cell form they are longer lasting,
capable of delivering more power per unit size,
and may be recharged.
2. In wet cell form they are lighter, deliver
more power per unit size and require less
maintenance.
The main disadvantage of the nickel-cadmium
battery is its high cost relative to conventional
dry cells and the lead- acid battery.
Nickel-Cadmium Cell Construction. The
active materials of the nickel-cadmium cell
(fig. 7-4) consist of nickel hydroxide on the
positive plate and cadmium hydroxide on the
negative plate. The electrolyte used in a nickel-
cadmium battery is a caustic alkaline solution
consisting of potassium hydroxide in distilled
water. Chemically speaking, this is just about
the exact opposite to the diluted sulfuric acid
used in the lead- acid battery.
The electrolyte of the nickel-cadmium cell
conducts current between the negative and positive
plates and reacts with them to produce electro-
chemical changes without producing any sig-
nificant change in its own chemical composition.
For this reason, it is not possible to determine
the charge state of a nickel-cadmium battery by
checking the electrolyte with a hydrometer;
neither can the charge be determined by a
voltage test because of the inherent characteristic
TERMINALS
VENT AND
FILLER CAP
CASE
SEPARATORS
PLATE
Figure 7-4. Nickel- cadmium cell.
236.40
SHIPBOARD ELECTRICAL SYSTEMS
that the voltage remains constant during 90 per-
cent of the discharge cycle.
BATTERY MAINTENANCE
In general, the maintenance required to main-
tain any battery is dependent on its use. Some
general information relating to the care, handling,
and stowage of batteries is listed below. For
detailed information relating to the maintenance
and safety precautions for lead-acid and dry cell
batteries, the manufacturer's technical manual,
Naval Ships' Technical Manual, Chapter 313
(9622), or the PMS should be consulted. For
detailed information relating to nickel-cadmium
batteries, maintenance and safety precautions as
well as other alkaline batteries, the technical
manual furnished with the battery, Naval Aircraft
Storage Batteries, NAVAIR 17-15BAD-1, or the
PMS should be consulted.
Dry Cell Maintenance
The common carbon- zinc dry cell battery is
popular largely because it is essentially main-
tenance free and very inexpensive. When used
beyond serviceable life, these batteries are
usually disposed of.
Alkaline versions of the dry cell are becoming
increasingly popular in commercial as well as
Navy equipment. The batteries are supplied as
sealed units. They are usually kept on float
charge by a battery charger built into the equip-
ment in which they are installed. Maintenance
is not usually required on these batteries and,
as with the common dry cell, they are usually
replaced when beyond their service life.
Because of chemical reactions within them,
common dry cells deteriorate with age whether
or not in use (25% to 50% energy is lost in 2
yearSo) Deterioration may be minimized by
storing dry cells in a cool location that is not
dehumidified.
Lead- Acid Battery
Maintenance
Although the PMS specifies minimum pre-
ventive maintenance for lead- acid batteries, con-
sideration should also be given to the application
and conditions under which the battery is used.
ENGINE STARTING BATTERIES. - Because
of the heavy demands on batteries used for
starting propulsion engines, ship's boat engines,
ship's service and emergency engine- generator
sets, they are particularly liable to failure,
Defects, which would hardly be noticeable in
a battery used for less severe service, could
result in total failure in an engine starting
sequence. Because these batteries are sometimes
subjected to the severities of salt spray and cold
weather, as in the ship's boats, they should
receive an increased amount of attention. You
will find it exceedingly difficult to explain to
your commanding officer why the ship's life boat
engine will not turn over or why the ship's
emergency generator will not start. These bat-
teries therefore require frequent checking ty
competent personnel.
Batteries subjected to cold weather should
be kept fully charged because:
1. Engines are harder to crank in cold
weather.
2. The electrolyte, being part water, can
freeze, causing damage to the battery and case,
As a rule, the greater the percentage of acid
in the electrolyte, the lower its freezing tem-
perature. As an example, electrolyte with a
specific gravity of 1.150 (equivalent to that found
in a discharged battery) will freeze at -15
F s while electrolyte with a specific gravity of
1.300 will remain unfrozen at temperatures down
to -95 F,
Grounds may be formed by dirt or acid on
battery tops and sides. The ground path, through
which current flows, can Tbe established from
the battery terminals through the acid and dirt
along the top and sides to the ship's hull,
Battery grounds are undesirable becauset
1. A ground in the vicinity of a battery may
furnish the spark necessary to ignite an ex-
plosive gas mixture, if present.
2. A ground on the battery may cause a
malfunction in the circuit to which the battery
is connected.
3. Leakage current from the battery through
the ground can cause dissipation of the energy
in the battery.
In addition to forming grounds, dirt on battery
tops and sides permits leakage current to flow
directly from one terminal through the dirt and
acid to the other terminal. This condition also
dissipates the energy of the battery.
For the reasons stated above, batteries must
be kept clean. All electrolyte, dirt, salt, corro-
sion, and foreign objects should be kept off
battery tops and sides. Dirt and foreign material
124
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
on the top of a battery case increase the like-
lihood of their falling into the battery and con-
taminating it when the vent plugs are removed.
In this respect, the presence of salt and saltwater
merit special concern of maintenance personnel
because chlorine gas is released when salt and
sulfuric acid are combined.
Nickel- Cadmium
Battery Care
The majority of nickel- cadmium batteries
under the cognizance of the electrical division(s)
are an integral part of electrical or electronic
equipment which, as a rule, have built-in battery
chargers that maintain the nickel-cadmium bat-
tery fully charged. These batteries are not
usually subjected to severe usage but are used
to supply power for a limited period to the equip-
ment in case of normal power failure.
Maintenance for the units should be carried
out as prescribed in PMS.
Dry Cell Safety
Precautions
1. When equipment operated by dry batteries
is to remain idle for more than 2 weeks, the
batteries should be removed and either scrapped
or stored.
2. Mercury-cell batteries may explode if
improperly used. To prevent this occurrence,
the following additional precautions must be
followed:
a. NEVER discharge a mercury-cell bat-
tery after the battery fails to operate the equip-
ment, or after the voltage falls below 0.9 volts
per cell.
b. NEVER leave the battery switch "on"
when the equipment is not in use, or after the
battery fails to operate the equipment.
c. NEVER impose a "dead short circuit 15
on a mercury cell, or allow it to become over-
heated. A temperature of approximately 400
F is sufficient to cause a mercury cell to
explode.
d. Mercury-cell batteries that have
reached the end of their shelf- life while in storage
should NEVER be issued to using activities.
e. Discard exhausted mercury-cell bat-
teries as soon as possible. Dead single and
multicell mercury batteries with steel jackets
should have holes punched in the jackets before
being discarded to release any gas which might
have formed.
Lead- Acid Battery
Safety Precautions
1. Keep flames and sparks of all kinds away
from the vicinity of lead- acid batteries.
2. Be sure to ventilate battery compartments,
which have been sealed, BEFORE entering the
compartment, turning on any lights, making or
breaking any electrical connections, or doing any
work in the compartment.
3. Be sure the ventilating apparatus of the
battery compartment is runningproperly BEFORE
starting a charge.
4. STOP the charge if ventilation is inter-
rupted, except in an emergency, and DO NOT
resume the charge until ventilation has been
restored.
5. Charge a battery at the rates given on
its nameplate.
6. When charging lead-acid batteries, NEVER
allow the cell temperature to exceed 125 F.
7 Keep the temperature of the battery com-
partment below 95 F, if at all possible.
8. Make NO repairs to battery connections
while current is flowing. NEVER connect or
disconnect batteries on the charging line without
first turning off the charging current.
9. When using tools around a battery, be
careful NOT to short circuit the battery terminals.
10. When mixing electrolyte, always pour the
acid slowly into the water; NEVER pour the
water into the acid. Guard skin and eyes against
splashes of acid with face shields, aprons, and
rubber gloves.
11. DO NOT store pure sulfuric acid in places
where temperatures below 50 F may be en-
countered.
12. Keep the electrolyte level above the tops
of separators.
13. Add only pure distilled water to a battery.
14. DO NOT, except in an emergency, discharge
the battery below the given low-voltage limit.
15. NEVER allow a battery to stand in a
completely discharged condition for more than
24 hours.
16. DO NOT operate the battery when it reaches
125 F.
17. All sparks should be avoided during re-
moval or replacement of batteries which are
located in compartments that may contain gasoline
fumes. Only tools with insulated handles should
be used. For batteries that are used with one
terminal grounded, the grounded terminal should
be disconnected first when the battery is removed
and connected last when the battery is being
replaced.
125
SHIPBOARD ELECTRICAL SYSTEMS
18. NEVER allow saltwater to enter a battery
cell because the interaction produces extremely
toxic chlorine gas. Also, saltwater should NEVER
be used to wash battery cases and jars,
19 Be sure all terminal connections are tight
to preclude sparks due to loose connections.
If acid or electrolyte from a lead- acid battery
comes into contact with the skin, the affected
area should be washed as soon as possible with
large quantities of freshwater, followed with an
application of a salve such as petrolatum, boric
acid, or zinc ointment. If none of these salves
is available, clean lubricating oil will suffice.
When washing the affected area, large amounts
of water should be used because a small amount
of water might do more harm than good in
spreading the acid burn.
If acid splashes into the eyes, flush them
immediately with large quantities of freshwater.
Report to sickbay as QUICKLY as possible.
Acid spilled on clothing may be neutralized
with dilute ammonia or a solution of baking soda
and water.
Nickel-Cadmium Battery
Safety Precautions
The electrolyte used in nickel-cadmium
batteries is a strong caustic alkaline solution of
potassium hydroxide as opposed to the sulfuric
acid solution used in lead-acid batteries. There-
fore, the antidotes used when parts of the body
are affected with potassium hydroxide will differ
from those used when parts of the body are
affected by sulfuric acid.
If the alkaline electrolyte gets on the skin,
wash the affected areas with large quantities
of water, or take a shower immediately. Neutral-
ize with a 3 percent solution of acetic acid and
water, vinegar, or lemon juice, and wash with
water.
If the alkaline electrolyte gets into the eyes,
flush them immediately with large quantities
of freshwater and wash the eyes with a weak
solution of boric acid, or a weak solution of
vinegar.
If alkaline electrolyte has been taken inter-
nally, drink large quantities of water and a
weak solution of lemon juice, orange juice, or
vinegar; follow with white of egg, olive oil,
melted butter, starch water, or mineral oil.
In all cases seek medical attention IMME-
DIATELY.
As with lead-acid batteries, the electrolyte
used in the nickel-cadmium battery is corrosive.
Serious burns will result if the electrolyte
comes in contact with any part of the body. Ust
rubber gloves, rubber apron, and protects
face shield when handling electrolyte.
Nickel- cadmium batteries should not Tbe stored
or serviced in the same areas with lead-aoM
batteries. DO NOT use the same tools, such as
screwdrivers, wrenches, syringes, hydrometers
and gloves for both battery types.
BATTERY CHARGING
EQUIPMENT
The battery charging equipment employed by
the Navy varies from the very small circuits
that provide the very low charging current to
float charge small nickel-cadmium batteries used
in electronic devices to the large motor-
generator and engine-driven generators used
to charge submarine storage batteries.
Battery charging equipment must be capable
of supplying voltages higher than that of the
battery that is to be charged, and must be capable
of supplying current commensurate with the
battery's charging rate.
The most common types of shipboard battery
charging equipment are the battery charging sys-
tems employed on ship's boats and the general
purpose battery chargers.
The battery charging systems employed in
the ship's boats are very similar to the systems
found in automobiles except that in most cases
they are designed to charge 24-volt batteries and
most automobile batteries are rated at 12 volts,
These systems consist of engine-driven gener-
ators or alternators which produce a d.c. voltage
which is slightly higher than the battery voltage,
During the first several minutes of operation,
the boat battery-charging system charges the
battery to its full capacity to replace all the
energy that was used to start the engine. After
this initial period the charging system continues
to charge the battery, supplying sufficient current
to maintain it on a float charge. In addition to
charging the battery, the charging system must
supply power to all the electrical loads on the
boat, while the engine is running.
The general purpose battery chargers em-
ployed aboard ships consist of the devices neces-
sary to convert the ship's alternating current
to a controlled direct current of the proper voltage
to charge batteries. These battery chargers are
usually capable of charging batteries rated at
various voltages.
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
The general purpose battery chargers are
used to charge batteries that are not installed in
systems with integral battery chargers. In addi-
tion, they are used to provide supplemental
charges to some batteries. For example, the
batteries in the ship's boats are subjected to
very heavy current drains during starting. The
boat's engine may not always be run long enough
to replace the energy used during starting and
during long periods of inactivity; it is natural
for the boat's batteries to lose energy. There-
fore, it is very common for boat batteries to
require charging from the ship's general purpose
battery chargers.
SMALL BOAT ELECTRICAL
SYSTEMS
The electrical systems found in small boats
vary according to size and the intended purpose
of the boat. In general, however, most boats
possess electrical systems necessary for the
operation of the boat's engine and navigational
lights.
The electrical systems associated with the
boat's engine consist of starting system, battery
charging system, and those electrically operated
instruments necessary to properly monitor the
engine's operation. These systems operate in a
manner identical to the same type systems found
in automobiles, except that, as stated before,
most small boat electrical systems operate at
24 VDC.
When built properly, each craft has navi-
gational lights provided by the manufacturer. The
number of lights and their locations are deter-
mined by the rules of the road governing the
area where the boat is to be used principally
(usually international rules of the road).
Electrical equipment aboard small craft is
subjected to unusually severe conditions
humidity, salt spray, vibration, oil, and grease
and will require a great deal of attention.
Navigation lights, because of their infrequent
use, are often overlooked during routine in-
spections, thus creating embarrassing situations
for electrical division personnel on more than
one occasion. Naval Ships' Technical Manual,
Chapter 583 (9820) contains more specific in-
structions relating to small craft electrical
equipment, including navigation lights and safety
precautions.
ELECTRICAL FORKLIFT
TRUCKS
Electrical forklift trucks (fig. 7-5) are used
primarily for handling and transporting heavy
Figure 7-5. Electric forklift truck.
127
5.58(77C)A
SHIPBOARD ELECTRICAL SYSTEMS
A - TYPE A RANGE
B~ TYPE 60 OVEN
C ~ TYPE 90 FRY KETTLE
48.8.11
Figure 7-6. Electric galley equipment.
materials in confined areas where engine exhaust
fumes cannot be tolerated. They are toeing used
in ever increasing nurntoers atooard naval vessels
of all types.
Large capacity lead- acid storage batteries
(36 or 24 volt) are used to furnish power for
the drive and lifting mechanisms. These batteries
are usually of such design that they are easily
replaceable. This feature makes it possible
to remove an exhausted battery and to replace
it with a fully charged battery from the ship's
battery locker, permitting continuous use of the
forklift.
The electrical components of the forklift
include the battery, motors for the drive and
lift mechanisms, and the control circuits requir
for their operations. The control circuits for tl
drive and lift motors usually consist of sol
state devices which provide smooth posith
control through an infinite number of varyir
speeds.
More detailed information regarding electri
forklift trucks can be found in the manufacturer'
technical manual for your particular equipmer
or in Electrician's Mate 3 & 2, NAVEDTR
10546.
ELECTRIC GALLEY
EQUIPMENT
Electric galley equipment comprises the heav
duty cooking and baking equipment installec
aboard naval vessels and consists essentiall]
of ranges, griddles, deep fat fryers, roasting
ovens, and baking ovens (fig. 7-6). This equipment
is supplemented by electric pantry equipment,
which includes coffee urns, coffeemakers, grid-
dles, hotplates, and toasters. The number and
capacity of the units in a galley installation
depends on the size and type of ship. Galley
equipment is normally designed for operatior
on 115-volt or 440-volt, 3-phase, 60-hertz, a.c.
power.
RANGES
Electric galley ranges are provided in type
A (36-inch), type B (20-inch), and type C (30-inch).
The ranges consist of a range-top section and an
oven section assembled as a single unit and a
separate switchbox designed for overhead or
bulkhead mounting. A type A range (fig. 7-6A)
has three 6 -kilowatt surface units and an oven
section with two 3-kilowatt enclosed heating units.
OVENS
A type 60 roasting oven (fig. 7-6B) consists
of separate ovens, each of which is thermally
insulated and operated independently of the
others. The roasting ovens are provided in either
two or three sections mounted one above the other.
Each oven has a separately mounted switchbox
which contains the fuses, contactors, and two
or three heat switches, one for each section.
128
Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT
The type number of the oven denotes the capacity
in pounds of raw meat per section.
The type 12 and type 18 baking ovens are
sectional type ovens with each section con-
stituting a separate oven, thermally insulated
and operated independently of the other sections.
Each section of the type 12 or type 18 oven has
a capacity of six standard five-loaf bread pans.
The type 12 oven consists of two sections mounted
one above the other. The type number denotes
the total bread pan capacity of the oven.
DEEP FAT FRYERS
Electric deep fat fryers are normally provided
in the type 23, type 45, and type 90 sizes. Each
has enclosed electrical heating units rated at
5 kilowatts, 10 kilowatts, and 18 kilowatts,
respectively. A type 90 deep fat fryer is shown
in figure 7-6C.
The heating units are immersed directly in
the fat to ensure maximum efficiency. The fryer
is equipped with an adjustable automatic tem-
perature control to maintain the fat at the desired
temperature. The thermostat control, located
on a panel at the front of the fryer, is provided
with an OFF position and the adjustable tem-
perature range of 250 to 400 F is displayed in
gradations on the control knob. The thermostat
operates contactors which, in turn, control the
circuits to the heating units.
A compartment located inside the fryer con-
tains the contactors, thermostat, heating unit
terminals, line terminal block, fuses, and line
switch. The compartment is equipped with a
removable panel for easy access to the control
devices.
Because of the fire hazards associated with
deep fat fryers, they have been equipped with
several safety devices. One of these safety
devices consists of a circuit breaker located
remotely from the deep fat fryer. The circuit
"breaker permits manual interruption of power to
the deep fat fryer in case of fire or any other
emergency. Also associated with the remote
circuit breaker is a high limit thermostat located
inside the deep fat fryer. If the main thermostat
in the fryer fails, permitting the oil temperature
to exceed 460 F, contacts in the high limit
thermostat close and cause the remote circuit
breaker to open automatically and interrupt power
to the deep fat fryer.
ELECTRIC GALLEY
EQUIPMENT MAINTENANCE
Some of the more common problems en-
countered with galley equipment are a result
of the environment, cooking grease, oils, and
high temperatures in which they operate.
One relatively common problem is corroded
connections due to prolonged exposure to heat and
cooking oils. Another commonproblem associated
with galley equipment is grounds which are
usually caused by carelessness on the part of
those who are responsible for the cleanness of
the equipment. Spilled water on electrical contacts
and damaged electrical insulation are not un-
common occurrences.
LAUNDRY EQUIPMENT
Laundry equipment aboard ship is comprised
of washers, extractors, and dryers. They may be
installed separately or in combinations. This
equipment operates primarily on 3-phase, 440
VAC, 60-hertz power. The fully automatic
washer-extractor with a card-o-matic program-
mer is a representative piece of equipment.
WASHER-EXTRACTOR
The cylinder of the washer-extractor (fig. 7-7)
has a 100 -pound dry weight capacity. A three-
motor system drives the cylinder through its
various wash/extract cycles by means of V-belts f
speed reducers, and an air-operated clutch. Elec-
tric solenoids control the supply of air for
operating the clutch, brake, drain and steam
valves, and detergent dispenser. Water level
is controlled by three pressure-operated level
switches; the water temperature is controlled
by three adjustable thermostats.
Though designed to operate automatically
(formula mode), the washer-extractor can operate
in the manual mode or in a combination of the
two modes. The sequence and duration of the
operations in the formula mode are controlled
by the card-o-matic programmer (fig. 7-8) which
also adds detergents and bleaches as pro-
grammed. In the manual mode, the machine
operator controls the duration and sequence of
the wash/ extract cycle by positioning switches
129
SHIPBOARD ELECTRICAL SYSTEMS
10
Legend:
1. OPERATING CONTROLS
2. REMOVABLE SIDE PANEL
3. DOOR BUMPER
4. LIFTING BAR
5. DATA PLATE
6. SUPPLY HOPPER
7. DRAIN VALVE AIR CYLINDER
10
8. WATER LEVEL BELLS
9. DRAIN VALVE
10. BASE PLATE
11. SIGHT GLASS
12. FRONT PANEL
13. TUB DOOR LATCH
Figure 7-7. -Front right view, Class 2258 Cascadex Washer- Extractor.
77,
as desired. Detergents and bleaches are added
as desired by manual operations.
Card-O-Matic
Programmer
The card-o-matic programmer controls every
operation of the washer-extractor when it is
operated in the automatic or formula mode. The
operator selects the proper formula card accord-
Sm^ the ^u f Washin S to be done - The
formula card, which is inserted into the card
reader portion of the card-o-matic programir
determines the wash time, water temperati
sequence of adding detergents, etc., during
entire operation. Incorrect programming of
formula card may cause the motor to s
LAUNDRY EQUIPMENT
SAFETY AND MAINTENANCE
As a rule, present day laundry equipme
complex in nature. This equipment is vit*
JDV^J uiJriviJDiM j.
20
19
16
1. RUN INDICATOR
2. STOP INDICATOR
3. FORMULA CARD WINDOW
4. SIGNAL INDICATOR
5. SIGNAL SWITCH
6. LEVEL SWITCH
7. MASTER SWITCH
8. SAFE ON SWITCH
9. STOP INCH PUSHBUTTON
10. INTERIOR LAMP (NOT SHOWN)
11. THERMOMETER
12. INCH START SWITCH
13. STEAM SWITCH
14. EXTRACT SWITCH
15. CARD ADVANCE WHEEL
16. DISCONNECT SWITCH
17. OVERLOAD RESET BUTTON
18. COLD WATER SWITCH
19. HOT WATER SWITCH
20. DRAIN VALVE SWITCH
77.330
Figure 7-8. Location of operating controls and indicators.
the health and morale of the crew and should
fee maintained to provide the best possible service.
Most laundry equipment is equipped with a
number of safety devices. If disabled, these
safety devices can result, and have resulted,
in shipboard fires, damage to equipment, damage
to clothing, and in many cases personnel injuries,
Special attention should be given these safety
devices during preventive and corrective main-
tenance with extra special attention being given
those devices designed to protect operator per-
sonnel.
FIN STABILIZER SYSTEMS
The fin stabilizer system is installed on
FF's and FFG's to counteract the rolling motion
of the vessel which results from wave motion
and high speed maneuvers. The fin stabilizer
systems installed on these ships are active,
which means that some form of energy is supplied
to move the fins. Though they are manufactured
by different companies, we shall describe only
the system designed by Sperry Rand since it is
considered a representative system. This system
131
SHIPBOARD ELECTRICAL SYSTEMS
provides a high degree of ship stability and
enhances ship performance.
GENERAL DESCRIPTION
The main components of the ship stabilizing
system are two machinery units, a control con-
sole, and two motor controllers (fig. 7-9).
Each machinery unit consists of a fin and
fin-actuating machinery and is designed to be
welded to the ship's hull.
The two main hydraulic pump units are
shock-mounted on the forward sides of the
machinery units. Each pump unit consists of a
variable delivery pump, a 50-hp electric-drive
motor, and accessories.
All roll measuring devices and equipment
for computing the required stabilizing actions
are housed within the control console. Its control
panel contains the control devices and indicators
for monitoring the fin stabilizer system operation.
PRINCIPLES OF
OPERATION
Wave action, which causes the ship to roll,
can be counteracted by applying righting or
stabilizing moments to the ship in the direction
opposite that of the disturbing wave action. One
method of producing the moments is by means
of two underwater fins. The capacity of these
fins to stabilize a ship depends on the speed of
140.183
Figure 7-9. Typical fin stabilizer installation.
the vessel, size of the fins, and the manner]
which they are controlled.
The fin stabilizer system, as shown in figu:
7-10, consists of the control system, which con
putes and orders the proper stabilizing momei
and the machinery units, which develop t
ordered stabilizing moment.
The roll sensors measure the rolling act-
caused by the disturbing wave action and ti
supply data to develop the required staMliz
moments. The computer servo unit orders the
servo to tilt the fin, creating a fin lift or fo
resulting from the combination of the fin
and ship's movement. A stabilizing mom
(or antiroll torque) results from the actior
this force on the lever arm between the :
and the ship's center of roll.
The equality in fin forces, or lifts, is assi
by equality of the ordered lift signals f
the computer servo unit and by measurer
of the actual lift exerted by each fin. The ord<
lift signal and the actual lift signal are c
pared in the positioning servos; any differ*
in them is used to change the fin angle i
actual lift is equal to ordered lift.
FIN STABILIZING
SYSTEM MAINTENANCE
Fin stabilizer maintenance personnel
strongly encouraged to refer to the mam
turer's technical manual throughout cor re
maintenance actions. Use of the technical m
will greatly aid in troubleshooting and rep a
this equipment, as is true with all other equipi
STEERING SYSTEMS
The steering system is considered one
most vital auxiliaries since its operati
necessary to maintain directional control
vessel. Because of the vital role steering sy
play, ships are usually provided with s
different methods of direction control,
method is made to operate as independent
possible of the others. Several different
supplies are provided to the steering s^
and several means of controlling the st<
systems are provided on each ship.
CONTROL SYSTEM
ROLL
SENSORS
COMPUTER
SERVO
UNIT
ACTUAL i PORT STABILIZER
ORDERED
STABILIZING
MOMENT
(ORDERED LIFT)
POSITIONING
SERVO
\
\
HYDRAULIC
SERVO
--*
Fl
ACTUAL
T
1
LIFT |_STARBOARD STABILIZE!
[ER^ J
SHIP'S ROLL MOTION
Figure 7-10. Block diagram of fin stabilizer system.
140,184
STEERING GEAR
The majority of steering gear installations
in new construction naval vessels are of the
electrohydraulic type. A typical electrohydraulic
steering system is illustrated in figure 7-11.
The electrohydraulic steering gear consists es-
sentially of (1) a ram unit and (2) a power unit*
Ram Unit
The ram unit is mounted athwartship and
consists of a single ram that operates in opposed
cylinders. The ram is connected by links to the
tillers of the twin rudders and is moved by the
oil pressure built up in either of the cylinders,
the oil from the opposite cylinder returning to
the suction side of the pump.
A rack is attached to the ram and engages
two gears (followup pinions), the rotation of
which is transmitted to the respective differential
control boxes through the followup shaft.
Power Unit
The power unit consists of two independent
pumping systems, which include two motor-driven
pumps, two transfer valves with operating gear,
relief valves, two differential control boxes, and
two " trick" wheels mounted on a bedplate, which
also serves as the top of an oil reservoir. Steer-
ing power is derived from either pumping system
acting alone. The power unit not in use serves
as a standby unit in case of emergency.
The two pumps (port and starboard) are
identical in size and design, and are of the
variable delivery axial piston type. Each pump
is driven by a 440 -volt, 3-phase, 60-hertz in-
duction motor through a flexible coupling.
The pumps of the power unit are connected
to the ram cylinders by a high-pressure piping
system. The two transfer valves are interposed
in this piping, and their positions determine
which pump is connected to the cylinders in the
ram unit. A hand lever and mechanical leakage
(not shown) is connected to the two transfer
valves in such a way that, by positioning the
lever, both of the transfer valves are operated
simultaneously. The hand lever is usually located
between the trick wheels and it has three positive
detent positions. The detented positions are
marked P, N, and S which denote port pump
connected to the ram, neutral (neither pump
connected to the ram) and starboard pump con-
nected to the ram, respectively. Usually, the
133
SHIPBOARD ELECTRICAL SYSTEMS
<M
00
oJ
a,
1
3
?-H
1
1
0)
s
a
I
Qjn.JLjrjDV-Att.x\.L/
land lever is also connected to remote motor-
starting switches, permitting the operator to
connect the selected pump to the ram and start
the pump drive motor in one quick operation.
This arrangement is most beneficial in the
event of failure of the operating unit because
it permits steering power to be shifted to the
standby unit with one swift motion.
The mechanical differential control box serves
to correlate the mechanical signals from the
followup shaft (which represents the rudder
position) and the trick wheel, or the remote
steering system (which represents the desired
rudder position). If the desired and actual mech-
anical signals are the same, the mechanical
output from the differential control box will
be zero. If the two signals are not in corre-
spondence, the differential control box will pro-
duce a mechanical output. The mechanical output is
used to control the pump and, therefore, the
SHIP'S
STEERING WHEEL
(HELM)
SH/P'S CONTROL (
"1
REMOTE
STEERING
CONTROL
SYNCHRO 1
TRANSMITTER
PILOT HOUSE
REMOTE STEERING
~\
l
I
L .
" /
! */o
~1 CONTROL CABLE
SELECTOR SWITCH
<jr o ^ j
! L PORT OFF STBD. j
-
PORT
REMOTE
STEERING
CONTROL
CABLE
STBOL
REMOTE
STEERING
CONTROL
CABLE
L_
WNSOLE
J
REMOTE
STEERING
SYNCHRO
RECEIVER
SELECTOR
SWITCH
STEERING GEAR MACHINERY
ROOM
| PORT OFF STBD.
...._._ 1 *A .** ^^ 1
,
| I
1 n c
k
FT SI
' 1
1
r> 1
i \ j
\ REMOTE STEERING
1 \ (CONTROL CABLE
1 [ 'SELECTOR SWITCH
1
|_ PORT
P
reo. J
\
PC
1
6
1
If \
\
1
1
1
1
1
i )
REMOTE STEERING
CONTROL STBD.
SYNCHRO RECEIVER
\_STBD. STEERING 6
DIFFERENTIA! REMOTE STEERING
CONTROL BOX CONTROL PORT
CONTROL BOX SYNCHRO RECEIVER
")RT STEERING GEAR UNIT
DIFFERENTIAL
CONTROL BOX
'EAR UNIT
27.393
Figure 7-12. Remote steering control system.
135
SHIPBOARD ELECTRICAL SYSTEMS
direction of hydraulic oil flow and pressure to
the rams. Oil pressure from the pump causes the
ram to move, which repositions the followup
shaft, and movement continues in the desired
direction until the differential control Tbox output
equals zero.
REMOTE STEERING
CONTROL SYSTEM
The remote steering control system provides
control from the pilothouse for normal steering.
Refer to figure 7-12. Movement of the pilot-
house steering wheel rotates a synchro trans-
mitter which is electrically connected to either
of the synchro receivers located in the electro-
hydraulic steering control mechanisms. Two
sets of cables are installed between the trans-
mitter and receiver synchros. To provide maxi-
mum protection from Tbattle damage, one set is
installed on the port side of the ship, and the
other is installed on the starboard side of the
ship. A selector switch is installed in the pil(
house and in the steering gear room to pen
selection of the control signal on either the pi
or the starboard cable. These two switcl
must be set to select the same cable dur
operation. A third selector switch, install
in the steering gear room routes the steer
control signal to either the port or starbo
synchro receivers located in the steering g
unit to be used. This switch should be in
OFF position when the trick wheel is to
used. As shown in figure 7-12, the switc
are aligned so that the port cable and
starboard synchro receiver are selected,
actual operation, any combination may be ui
During remote control operation, the syncl
transmitter in the pilothouse drives the selei
synchro receiver. The receiver synchro meet
ically drives the input shaft of the differei
unit which controls the pump unit. The t
wheel may be used to provide a mechar
input to the differential control unit when i
engaged. The trick wheel and synchro rece
inputs are mechanically the same.
136
CHAPTER 8
ALARM AND WARNING SYSTEMS
Although they often constitute little more than
a power source, a switch and a signaling
device, the alarm and warning systems of the
various Interior Communications systems are ex-
tremely vital to any ship's operation,. Although
simple in design and principles of operation,
the importance of the alarm and warning systems
cannot be overemphasized. They warn watch-
standers of conditions that are dangerous to
personnel or of conditions that could result in
equipment damage if the equipment is allowed
to operate under those conditions for an extended
period*
Over the years an attitude of indifference
towards the alarm and warning systems has
prevailed to the extent that, on any given naval
unit, a number of these systems could be in-
operable with little or no effort being expended
to correct the problems. As a rule, the alarm
and warning systems in the engineering spaces
are the most seriously degradedo This may be
attributed to three major reasons:
1 These systems are subjected to extreme
humidity and temperatures.
2, The likelihood of physical damage to the
systems is much greater because heavy equipment
is rigged into and out of the spaces.
3. The maintenance and testing of the alarm
and warning systems usually require the efforts
of individuals from at least two separate divisions.
Effective coordination of the efforts of two
or three divisions is difficult. Personnel do
not arrive on station at the appointed time,
therefore, man-hours are lost and disinterest
grows. Those people who have no time to waste
hesitate to assign their men to these details.
The situation can continue to deteriorate to the
point that efforts cease.
As an officer in the Engineering Department
you should ensure that each of the alarm and
warning systems functions entirely as it was
designed to do, and that every effort is made
to coordinate the testing of all the components
within the alarm system by simulating the con-
ditions which the alarm is intended to detect.
A listing of some of the alarm and warning
system s with their circuit designations and classi-
fications is contained in table 8-1. The principal
components of alarm and warning systems are
switches or contact makers, relays, thermostats,
and audible and visual signals.
SWITCHES
Switches used with alarm and warning systems
include m anual lever-operated switches, pressure
and thermostatic switches, mechanical switches,
and water switches. Relays are used to open and
close circuits which may operate indicating
lights, annuciators and/or audible signals.
LEVER-OPERATED SWITCH
Many types of lever-operated switches (fig.
8-1) are used in Navy alarm and warning systems
to complete electrical circuits to various types
of audible and visual alarm signals. Two types of
standard switches are available. One type has a
spring return mechanism, and the other type
has a positive detent mechanism. The type of
switch used depends on the circuit in which
it is installed.
Special switches are used where the standard
switches cannot be used. For example, the
diving alarm switch on the submarine bridge must
be pressure proof. For submarine service, a
distinctive shape is used for the operating lever
knob or heads of alarm switches in conning
137
SHIPBOARD ELECTRICAL SYSTEMS
Table 8-1. Alarm and Warning Systems
Circuit
System
Importance
Readiness Class
BZ
Brig cell door alarm and lock operating
NV
4
BW
Catapult Bridle Arresterman safety Ind.
NV
1
CX
Bacteriological Lab. & Pharmacy Comb. Refer
Failure
NV
1
DL
Secure communications space door position
alarm
NV
1
DW
Wrong direction alarm
V
2
EA
Reactor compartment or fireroom emergency
alarm
NV
1
IEC
Lubricating oil low pressure alarm-
propulsion machinery
sv
2
2EC
Lubricating oil low pressure alarm-
auxiliary machinery
sv
1
1ED
Generator high temperature alarm
sv
1
2ED
Oxygen-nitrogen generator plant low tem-
perature alarm
NV
1
EF
Generator bearing high temperature alarm
SV
1
EG
Propeller pitch control, hydraulic oil system
low pressure alarm
SV
2
EH
Gas turbine exhaust high temperature
alarm
sv
1
2
(aux. machinery
(prop, machiner;
EJ
Feed pressure alarm
sv
1
1EK
Pneumatic control air pressure alarm
NV
2
3EK
Catapult steam cutoff and alarm
NV
2
XEL
Radar cooling lines temperature and flow alarm
NV
1
EP
Gas turbine lubricating oil high temperature
alarm
SV
1
2
(aux. machinery
(prop, machiner
1EQ
Desuperheater high temperature alarm
SV
1
2EQ
Catapult steam trough high temperature
alarm
sv
2
27.3
138
njurvruvi .CVLVU wrirxiNiiNvjr o ID1 JDlVIo
Table 8-1. Alarm and Warning Systems continued
Circuit
System
Importance
Readiness Class
3ES
Reactor fill alarm
V
1
ET
Boiler temperature alarm
NV
1
EV
Toxic vapor detector alarm
sv
1
1EW
Propulsion engines circulating water high
temperature
sv
1
2EW
Auxiliary machinery circulating water high
temperature
sv
1
EZ
Condenser vacuum alarm
sv
2
F
High temperature alarm
sv
1
4F
Combustion gas and smoke detector
sv
1
9F
High temperature alarm system-ASROC
launcher
sv
1
11F
FBM storage area temperature and humidity
alarm
sv
1
12F
Gyro ovens temperature and power failure
alarm
sv
1
FD
Flooding alarm
NV
1
FH
Sprinkling alarm
sv
1
FL
Flight Deck Landing Area Status Light
Signal system
NV
2
FR
Carbon dioxide release alarm
NV
1
FS
Flight Deck Readylight Signal system
NV
2
FZ
Security alarm (CLASSIFIED)
V
1
4FZ
Torpedeo alarm (CLASSIFIED)
V
1
HF
Air flow indicator and alarm
sv
1
LB
Steering Emergency Signal system
NV
2
LS
Submersible steering gear alarm
SV
2
27.352.1
139
SHIPBOARD ELECTRICAL SYSTEMS
Table 8-1. Alarm and Warning Systems continued
Circuit
System
Importance
Readiness Class
MG
Gas turbine overspeed alarm
SV
1
2
(aux. machinery)
(prop, machinery)
NE
Nuclear facilities air particle detector alarm
NV
1
NH
Navigation Horn Operating System
NV
2
QA
Air lock warning
NV
1
QD
Air filter and flame arrester pressure differen-
tial alarm, or gasoline compartment exhaust
blower alarm
V
1
QX
Oxygen-nitrogen plant ventilation exhaust alarm
SV
1
RA
Turret emergency alarm
NV
1
RD
Safety observer warning
NV
2
RW
Rocket and torpedo warning
SV
3
4SN
Scavenging air blower high temperature alarm
V
2
SP
Shaft position alarm
NV
2
TD
Liquid level alarm
NV
1
1TD
Boiler water level alarm
NV
1
2TD
DeaeratLng feed tank water level alarm
NV
1
5TD
Reactor compartment bilge tank alarm
SV
1
6TD
Primary shield tank, expansion tank level alarm
NV
1
7TD
Reactor plant fresh water cooling expansion tank
level alarm
NV
1
8TD
Reactor secondary shield tank level alarm
NV
1
9TD
Lubricating oil sump tank liquid level alarm
SV
1
11TD
Induction air sump alarm
SV
1
12TD
Diesel oil sea water compensating system tank
liquid level alarm
SV
1
14TD
Auxiliary fresh water tank low level alarm
NV
1
27.3
rx.Lj.tt.ruvi
WrllxlNliNljr d ID 1 JMVlD
Table 8-1. Alarm and Warning Systems continued
Circuit
System
Importance
Readiness Class
16TD
17TD
Pure water storage tank low level alarm
Reserve feed tank alarm
SV
NV
1
1
18TD
Effluent tanks and contaminated laundry tank
high level alarm
V
1
19TD
Sea water expansion tank low level alarm
SV
1
20TD
Gasoline drain tank high level alarm
SV
1
21TD
Moisture separater drain cooler high level alarm
NV
1
24TD
Reactor plant on board discharge tank level alarm
V
1
25TD
Crossover drains high level alarm
SV
1
29TD
Sonar dome fill tank low level alarm
SV
1
30TD
JP-5 fuel drain tank high level alarm
SV
2
TW
Train Warning system
NV
1
W
Whistle Operating System
NV
2
Legend:
V-Vital SV-Semivital NV-Nonvital.
1 Continuously energized-supply switch color code yellow.
2-Energized when preparing to get underway, while underway, and until the ship is secured-
supply switch color code black.
3 Energized during condition watches -supply switch color code red.
4-Energized only when required-supply switch color code white.
All electronic type alarm systems formerly designated as circuits CA, FC, FW, G, GD, GJ, GN,
and GP are now classified as a portion of the respective announcing system with which they are
associated*
27.352.1
140.4
Figure 8-1. Lever -operated switch (manual
contact maker).
tower and control room (where illumination
is low) to avoid confusion in operating the proper
switcho A square- shaped knob is used for the diving
alarm switch, a star-shaped head for the collision
alarm switch, and a standard round head for
general alarm
Lever-operated switches are used in such
systems as the fireroom emergency signal, 1
general alarm, chemical- attack alarm, steering
emergency signal, whistle operation, life buoy
release, and flight-crash signal.
PRESSURE SWITCH
Pressure-operated switches (fig. 8-2) contain
either a bellows or a diaphragm that works
against an adjustable spring. The spring causes
the contacts to close or open automatically when
141
SHIPBOARD ELECTRICAL SYSTEMS
77.119(140)
Figure 8-2 Pressure switch type IC/L.
Thermostatic Switch Type IC/N I
The type IC/N therm ostatic or temperature- j
operated switches (fig. 8-3) are constructed
similarly to the previously discussed pressure (
switches. Each switch contains a bellows whicl;
works against an adjustable spring. The spring!
causes the contacts to close or open automatically!
when the operating temperature exceeds or fallsj
below a specified value The motion of the!
bellows is produced by a sealed~in liquid that ;
expands with rising temperature. The sensitive
element containing this liquid may be an integral
part of the switch or it may be located in a
remote space and connected to the switch by a
capillary tube.
The therm ostatic switch is available to sense
a wide range of temperatures; each switch is
adjustable to a specific temperature within its
range. The therm ostatic switch physically re-
sembles the pressure switch except that a sensi-
tive element or capillary tube is connected when
the pressure source would be connected to tin
pressure switch*
The IC/N temperature-operated switches ar
used with the circulating-water high-temperatur
the operating pressure falls below or exceeds
a specified value. These switches are available
to sense pressure changes in ranges of 0-15,
15-20, 50-100 pounds, etc. Special switches are
available which sense very high pressure or
vacuums. The exact pressure at which the con-
tacts close or open is adjustable, as long as
the desired setting is within the range of the
switch.
Pressure-operated switches are used with
the lubricating oil low-pressure alarm system,
pneumatic control air pressure alarm system,
and booster-feed pressure alarm system, as
well as others. Pressure-operated switches are
also used to control electrical circuits; for
example, to start an electrically driven emergency
lube oil pump when the pressure from the main
pump falls below a specified value.
THERMOSTATIC SWITCHES
The Navy uses two basic types of therm ostatic
switches for alarm circuits: type IC/N and
mercury.
77.1!
Figure 8-3. Thermostatic-operated switch, Ty
IC/N.
142
Chapter 8 ALARM AND WARNING SYSTEMS
27.308
Figure 8-4* Mercury thermostat,,
alarm system, cruising- turbine exhaust alarm
system, and generator- air high-temperature
alarm system, as well as others.
Mercury Thermostatic Switch
The sensitive unit of the mercury thermostatic
switch (fig. 8-4 and 8-5) is similar in construction
to an ordinary mercury thermometer, except that
three metal electrodes are inserted into the
glass enclosure.. The electrodes complete contact
with the mercury column as the height of the
mercury increases in the glass tube. An increase
in temperature results in the mercury's shorting
out the upper and lower contacts which completes
the electrical circuit; the middle contact is
used in conjunction with the supervisory circuit
which will be discussed later in this chapter.
The thermostats are designed to close their
contacts at temperatures of 105, 125, or 150F.
LINE
27.309
Figure 8-5. Mercury thermostat sensitive unito
143
SHIPBOARD ELECTRICAL SYSTEMS
Except for differences in temperature ratings,
the thermostats are similar. A defective thermo-
stat must be replaced with one that has the same
temperature rating* Mercury thermostat switches
are used in ship's fire alarm system circuit F.
WATER SWITCH
Water switches consist of a pair of contacts
mounted on an insulated base within a cast
fitting (fig, 8-6). The switch is mounted in the
m agazine flooding system with a sprinkling control
valve installed between the switch and the firt
main. When the sprinkling control valve it
opened, salt water floods the switch casting ani
shorts out the contacts, thereby permitting i
current flow of sufficient value to operate th<
alarm. The resistor in figure 8-6 is used i
conjunction with the supervisory circuit an
will be discussed later in this chapter.
SECTION B-B
LEGEND
(T) SPACER. (J) 1/8" STANDARD PIPE PLUG.
(T) CONTACTS. (T) CLAMP.
i\ "0" RING GASKETS. (7) RESISTOR, 7000 OHMS.5 WATT.
SUGGESTED METHOD OF MOUNTING WATER SWITCH
-SPRINKLING CONTROL VALVE
INSTALL WATER SWITCH ON
UNDERSIDE OF PIPING ON
THE DRY SIDE OF THE
SPRINKLING CONTROL VALVE
\_
WET SIDE
WATER SWITCH
Figure 8-6. Water switch.
144
140.
Chapter 8 ALARM AND WARNING SYSTEMS
LIQUID-LEVEL
FLOAT SWITCH
The liquid-level float switch (fig* 8-7) is used
in tank and bilge level alarm circuits,, T"ie switch
assembly consists of a center column with a
magnetically operated reed switch encapsulated
inside it, A float, containing a magnet, surrounds
the center column and is free to move up and
down the column The movement of the float
with its magnet causes the contacts of the reed
switch to open or close. By mounting the switch
assembly at a predetermined level in a tank or
bilge, it can be made to give above or below
normal liquid level indications.
The liquid level float switch is used in the
flooding alarm circuit FD, as well as others.
MECHANICAL SWITCH
Mechanical switches are employed to indicate
the position of a component or to sound an alarm
if the component is not in the proper position.
These switches usually contain microswitches
which are actuated by either a cam or a push-
operated plunger. The push- action plunger mech-
anism utilizes a straight line movement of the
shaft to operate a microswitch.
The cam-action switch consists of two micro-
switches operated by two adjustable cams mounted
on the rotor shaft (fig. 8-8.) The cam-action
mechanism utilizes a rotary motion of the shaft
to move cams, which in turn operate micro-
switches. The points of operation of the micro-
switches are varied by adjustment of the angular
positions of the cams with respect to the shaft
on which they are mounted. Mechanical switches
are used in the secure communications space
door position alarm (circuit DL); wrong direction
alarm (circuit DW); airlock warning (circuit
QA); as well as in other circuits.
COMBUSTION GAS AND
SMOKE DETECTOR
The combustion gas and smoke detector (fig.
8-9) is an electronic switch. The presence of
smoke or combustion gases causes the internal
resistance of the detector to decrease drastically,
thereby allowing it to conduct a larger current
in much the same way as the closing of the
mechanical contacts of an ordinary switch. The
detector contains small quantities of radium
and, therefore, should be handled and disposed
SHAFT
.MICRO
SWITCHES
ADJUSTABLE
CAMS
Figure 8-7. Float switch.
140.63X
140.6
Figure 8-8. Cam-action mechanical switch.
145
SHIPBOARD ELECTRICAL SYSTEMS
Figure 8-10. Cowbell type IC/B354.
27.2S
27.310
Figure 8-9 Combustion gas and smoke detector
head*
of in accordance with current directives for
radioactive material. The combustion gas and
smoke detector is used in the combustion gas and
smoke detection .system 1C circuit 4F.
AUDIBLE SIGNALS
There are many types of audible signals in
use aboard Navy ships The principal types of
audible signals are bells, buzzers, horns, and
sirens. Electronic signals are used for some
applications on new construction ships, Ths
type of signal used depends on the noise level
at the location and on the kind of sound desired,
BELLS AND BUZZERS
Bells used with alarm and warning systems
may be either aoC, or dc a operated, either
watertight or watertight explosion proof con-
struction, with either circular or cowbell-shaped
gongs*
Alternating current bells have any one of three
types of gongs; circular 3-inch diameter, circular
8-inch diameter, and the cowbell type (fig. 8-10).
Direct current bells have any one of thre
types of gongs: circular 2 1/2-inch diainete:
circular 8-inch diameter (fig. 8-11), and cowbe!
type.
Buzzers are used only in relatively quit
spaceSo Buzzer, type IC/Z1D4 (fig. 8-12), i
d.c operated and has make and break contact
Figure 8-11, IC/B2D4 bell.
27,2i)
Chapter 8 ALARM AND WARNING SYSTEMS
Buzzer, type IC/Z1S4, is a.c. operated and has
no contacts*
HORNS \ND SIRENS
Nonresonated horns utilize a diaphragm actu-
ated by a vibrating armature to produce sound of
the required intensity,,
Resonated horns (fig. 8-13) also use dia-
phragms and, in addition, have resonating pro-
jectors to give the sound a distinctive frequency
characteristic. The resonated horn is designed
in a variety of types differing as to intensity,
frequency, or power requirements.
Motor-operated horns, or klaxons, utilize
electric motors to actuate the sound-producing
diaphragm So These horns are used in the diving
alarm system aboard submarines, as well as
in other circuits. Figure 8-14 is a cutaway view of
a motor-operated horn.
Figure 8-1 3 Resonated horn a
27.300
(\J BEARING, REAR OILITE
(?) MOTOR HOUSING
(3) MOTOR SUPPORT, REAR
MOTOR SUPPORT, FRONT
(?) FILTER
(6) INSULATOR
(7) RATCHET
ANVIL
() DIAPHRAGM
(io) FRONT COVER ASS'Y
Figure 8-12.--IC/Z1D4 buzzer.
27.299 Figure 8-14.-
27.300
-Cutaway view of motor-operated
horn.
147
SHIPBOARD ELECTRICAL SYSTEMS
Sirens are used in very noisy spaces to sound
urgent alarms. The sound is produced by an
electric motor driving a multiblade rotor past
a series of ports or hole sin the housing (fig, 8-15).
The sound is made by the air as it is forced
through the ports. The frequency of the sound
depends on the number of ports, the number of
rotor blades, and the speed of the motor.
ELECTRONIC SIGNAL UNITS
The type IC/E1D1 electronic signal unit (fig.
8-16) is designed as a power failure alarm. The
unit contains an electronic solid state oscillator
which produces an audible signal upon loss of
power to the bus that is being monitored by the
alarm unit*
The oscillator receives its power from a
small nickel-cadmium battery which is maintained
on a low charge when the monitored bus is
energized. The unit will operate on 115 volts,
d.c* or a.c. (60 Hz or 400 Hz), without modification.
VISUAL SIGNALS
Visual signals are used in a great many
alarm and warning systems as an additional
means of identifying the alarm being sounded.
Audible and visual signals are of ten used together
In noisy spaces audible signals are supplemented
by visual signals, and in brightly lighted spaces
Figure 8-1 5,-- Siren.
27.301
27.302
Figure 8-16. Electronic signal unit type IC/E1D1,
visual signals are supplemented by audible sig-
nals. In many instruments the same audible device
is used in combination with several visual indi-
cators. The principal types of visual signals
are lamp-type indicators and annunciators sucl
as those utilized in alarm switchboards and panels,
LAMP- TYPE INDICATORS
Standard watertight, lamp- type indicators are
designed as single-dial, 2-dial, (fig. 8-17) , 4-dial,
or 6-dial units. Two lamps are connected io
parallel and mounted behind each dial to provide
protection against the loss of illumination ID
case one lamp burns out* A colored-glass disk
and sheet-brass target engraved with the alarm
identification are illuminated from the rear tj
the two lamps. Glass disks are furnished IE
eight standard colors, dependent on the applica-
tion.
The power to the lamps is in parallel witt
the audible signal. When the audible signal
sounds, the lamps illuminate the colored glass
148
Chapter 8 ALARM AND WARNING SYSTEMS
/#^
27.303.1
Figure 8-17 Lamp type indicator.
and brass target of the indicator and identify
the alarm being soimdedo This type of indicator
is used with various alarm system s
ALARM ANNUCIATORS
There are two basic types of alarm annun-
ciators in general use. Each of these types
supervises the circuit to which it is connected,
providing alarm signals in the event of an alarm
condition, and supervisory signals in the event
of an open circuit between the indicator and the
remote alarm sensor (switch).
The alarm annunciator measures the current
flow through the circuit that is connected to it
and differentiates between a normal, an alarm,
or an open circuit condition,, The circuit that
is connected to the alarm annunciatox* has a
149
SHIPBOARD ELECTRICAL SYSTEMS
resistor attached across the last switch in the
line of that circuit, as shown in figure 8-18.
This resistor, called the supervisory resistor,
permits a limited amount of current to flow
through the circuit when the switch is open.
This limited amount of current flow represents
the normal circuit condition. Less current flow
through the circuit or an open circuit results
in supervisory signals being produced; more
current flow through the circuit as when the
switch closes, results in alarm signals being
produced.
Alarm annunciators are used in conjunction
with larger assemblies to form alarm switch-
boards or switchpanels which may supervise
from 2 to more than 50 individual alarm circuits.
Two-Line Alarm Unit
The two-line alarm unit (fig. 8-19) provides
equipment for supervising two circuits. Each
circuit has an alarm-target relay, a supervisory-
target relay, and a test-cutout switch. The two-
line unit has two alarm target relays mounted side
by side at the rear near the bottom of the unit
paneL Each alarm target relay has conti
which operate external alarm signals and
an indicator drum which projects a red ta:
into the square opening in the face of the pi
when the relay is operated. The two supervig
target relays have contacts that operate exte:
supervisory signals and have indicator dr\
that project a yellow target into the sqt
openings in the face of the panel when the r<
is restored.
Under normal conditions the current flov
through the supervisory resistor is suffic
to operate the supervisory relay but not
alarm relay. Therefore, neither the red all
target nor the yellow supervisory target is vis
in the openings in the front panel.
The test-cutout switch is a three-posi
switch. In the normal position the alarm indict
monitors the remote switch for alarm or sup
visory conditions. In the test position the sw
simulates an alarm condition, and is used to
the components internal to the alarm indie?
and the external alarm signals. THE T]
POSITION VERIFIES ONLY THAT THE ALA
SUPERVISORY
RESISTOR
J ASWITCH
f 1
ALARM
ANNUNICATOR
MERCURY
THERMOSTATS
JL
ALARM
ANNUNICATOR
SUPERVISORY
RESISTOR
Figure 8-18. Basic alarm circuit with supervisory resistor.
150
27.9
Chapter 8 ALARM AND WARNING SYSTEMS
SUPERVISORY
RELAY and TARGET
ALARM
RELAY and TARGET
/'
TEST and 4vt
CUTOUT SWITCH ""
SIDE VIEW
FRONT VIEW
Figure 8-1 9 . Two-line alarm unit.
27.304
INDICATOR IS FUNCTIONING PROPERLY. IT
DOES NOT VERIFY THAT THE REMOTE SEN-
SORS WILL FUNCTION AS THEY WERE IN-
TENDED. The cutoutpositionisusedto silence the
external alarm or the supervisory audible signal.
IC/M Alarm Module
The IC/M alarm module performs the same
function as the two-line alarm unit previously
discussed. This unit is of more recent design
than the two-line alarm unit, and it must be
employed in an alarm switchboard which contains
an audio generator. The audio generator produces
audible signals for alarm and supervisory con-
ditions.
The alarm module (fig. 8-20) has a manual
selector switch for placing the module in either
NORMAL, STANDBY, CUTOUT, or TEST modes
and has a divided, lighted display, either half
of which can show a steady or a flashing red
light or no light, as required.
Under normal conditions, the upper lamp is
"on steady," and the lower lamp is off (fig. 8-21).
During an alarm condition, the upper lamp flashes
and a wailing tone from the associated switchboard
sounds.
To acknowledge an alarm , the switch is
shifted to STANDBY and the audible alarm is
silenced while both the upper and lower lamps
are "on steady." After the alarm condition is
cleared, the lower lamp flashes while the upper
lamp goes out. A pulsating tone from the associated
switchboard informs the operator to return the
switch to the NORMAL position.
If the supervisory resistor on the circuit to
the switch should open, the upper lamp goes
out while the lower lamp is "on steady"; a pulsa-
ting tone from the associated switchboard alarm
sounds when the module is in the NORMAL mode.
Then, the alarm is silenced by placing the mode
selector switch to CUTOUT. In this position
the lamps indicate the same as thev do for
supervisory failure: top lamp out, lower lamp
"on steady," no audible alarm.
151
SHIPBOARD ELECTRICAL SYSTEMS
140.122
Figure 8-20. IC/M alarm module.
Placing the mode selector switch in the TEST
position simulates an alarm condition. For this
position the upper lamp flashes while the lower
lamp is out, A wailing tone alarm sounds just
as it does for an alarm condition in the NORMAL
mode.
ALARM PANELS AND
SWITCHBOARDS
Alarm panels and switchboards are used in
conjunction with a majority of the alarm systems
which monitor equipment or spaces, such as the
low-lubricating oil pressure alarm, flooding and
fire alarm systems.
ALARM SWITCHBOARDS
There are two basic types of alarm switch-
boards. While both perform the same functions,
one uses the two-line alarm units, and the other
uses the IC/M alarm module. Alarm switchboards
are usually installed in spaces that are con-
tinuously monitored, both in port and underway,
Switchboards supervise a large number of sensor
circuits which are installed in numerous locations
throughout the ship, such as the mercury thermo-
stats employed in 1C circuit F.
Two-Line Unit Alarm
Switchboard
The two-line unit alarm switchboard is shown
in figure 8-22, The upper section comprises the
alarm panel which contains an alarm bell, a
test light, a trouble buzzer, two ground-detector
lamps, a power available lamp, a trouble test
lamp, and a test key. An extension signal relay,
capable of operating up to four alarm bells
located at remote stations on the ship, is mounted
at the rear of the alarm panel. As long as the
power supply to the switchboard is maintained,
the power available light at the center of the
panel glows.
The lower section of the two-line unit alarm
system switchboard (fig. 8-22) may consist of as
many 10-line or 20-line panels as are necessary to
accommodate the total number of high-
temperature circuit F , or water- sprinkling circuit
FH stations aboard the ship. Six 10-line panels
capable of accommodating 60 lines are shown in
figure 8-22. The switchboard apparatus for each
two lines is mounted together in a removable
alarm unit as shown in figure 8-19, Five of these
2-line units are arranged to make up a 10-line
panel, A nameplate located above the cutout
test key identifies the compartment or the spaces
served by that line.
ALARM PANELS
Alarm panels are produced in two standard
sizes to supervise two or four remote sensors.
The alarm panel enclosure houses one or two
of the standard two-line alarm units. Alarm panels
are usually .mounted adjacent to the equipment
which is monitored by the alarm sensors.
Type IC/SM Alarm
Switchboard
The type IC/SM supervisory alarm switch-
board (fig. 8-23) provides centralized monitoring
of remotely located sensors. The features of the
type IC/M alarm module, as previously explained,
have been incorporated into this alarm switch-
board,,
152
Chapter 8 ALARM AND WARNING SYSTEMS
NORMAL
NORMAL ALARM
OR TEST
C0MPT,
STAND-BY ALARM
OOMFT.
WAILING
STANDBY
ALARMCLEARED
CUTOUT
COMPT.
1-126-A
SUPERVISORY
FAILURE
COMPT.
M26-A
COMPT.
1-126-A
PULSATING
~- PULSATING
Figure 8-21. 1C /SM visual displays and audible outputs.
140.123
The upper section of the switchboard houses a
speaker, signal generator, audible signal silence
control switch, lamp dimmer, power supplies,
buses, and ground detector lamps. The audible
signal silence control switch is utilized to disable
the audible alarm feature, while the visual alarm
system remains fully operational. The audible
signal silence indicator alerts personnel when the
audible signal is not operational,,
The lamp dimmer affects all the module indi-
cating lights except the alarm condition lights
which continue to flash at a full brilliance.
SHIPBOARD ELECTRICAL SYSTEMS
ALARM TEST KEY
TEST LIGHT
ALARM BELL
ALARM TEST LAMP
POSITIVE GROUND
DETECTOR LAMP
BLOWN FUSE
INDICATOR
FOR EXTENSION
SIGNAL CIRCUITS
FROUBLE BUZZER
TROUBLE
TEST LAMP
NEGATIVE GROUND
DETECTOR LAMP
POWER AVAILABLE
LAMP
27.307
Figure 8- 22* Two-line unit alarm switchboard.
154
Chapter 8 ALARM AND WARNING SYSTEMS
GROUND
DETECTION
LAMPS (fa-)
AUDIBLE
SIGNAL
SILENCE
CONTROL
LAMP
DIMMER
AUDIBLE
SPEAKER
AUDIBLE
SIGNAL
SILENCE
INDICATOR
MAIN
POWER
FUSE
INDIVIDUAL
DISPLAY
MODULES
(10 per Line)
Figure 8-23, IC/SM switchboard showing 10 active modules in place.
140,121
ALARM SYSTEMS plus the different types of switches, indicating
devices, and signals, employed in each circuit
make it unique to other circuits. Several of the
As previously stated, most alarm systems various alarm systems will be discussed in this
consist of a switch, power supply, and some section. Diagrams are included to aid you in
type of indicating device, whether it be audible, understanding how the various components we have
visual, or a combination of the two. The par- described in this chapter are employed to form a
ticular equipment or component being monitored complete alarm system fl
155
SHIPBOARD ELECTRICAL SYSTEMS
HIGH-TEMPERATURE
ALARM SYSTEM
The high-temperature alarm system (circuit
F) is used aboard ship to detect and warn of fires
or overheated conditions in designated com-
partments and spaces. Usually this circuit em-
ploys the mercury-type thermostats and one of
the two types of alarm switchboards (figo 8-24)
The thermostats are installed on the overhead
and require a free circulation of air a
The 125 and 150 thermostats are normally
installed in storerooms, paint lockers, and similar
spaces that house combustible stores. The 105
F thermostat is normally installed in magazines.
As many thermostats as are needed for the
prompt detection of a fire can beconnectedto any
one line. If more than one thermostat is used in a
compartment, only one supervisory resistor is
required. When any one of the thermostats in the
group is overheated, the alarm operates,, These
PAINT LOCKER
MT.51 MAGAZINE
POWER FROM
MAINIC
SWITCHBOARD
27.379
Figure 8- 24 ~- High- temperature alarm system,
156
Chapter 8 ALARM AND WARNING SYSTEMS
thermostats, or groups of thermostats, are con-
nected to the alarm switchboard by multiconductor
cable* Each circuit on the alarm switchboard is
marked to designate one compartment, and the
thermostat, or group of thermostats, installed
in each compartment is connected to the circuit
marked for that compartment.
SPRINKLING ALARM
SYSTEM
The sprinkling alarm system, circuit FH, is
basically the same as the high-temperature alarm
system except that water switches (fig. 8-6) are
used instead of mercury thermostats.
COMBUSTION GAS AND
SMOKE DETECTOR SYSTEM
The combustion gas and smoke detector system
(circuit 4F) detects and warns of the presence of
combustion gases or smoke. The alarm circuits
operate similar to the high-temperature fire
alarm circuits, A combustion gas and smoke
detector (fig 8-9) is used as the sensing device*
CIRCULATING-WATER,
HIGH-TEMPERATURE
ALARM SYSTEM
The circulating-w a t e r , h i g h- temperature
alarm system, circuits 1EW and 2EW, auto-
matically indicates when the circulating-water
temperature of the main propulsion diesel engines
or the large auxiliary diesel engines rises above
the predetermined maximum limit. When the
system is used for the main engines, the circuit
is designated 1EW; when the system is used
for auxiliary engines, the circuit is designated
2EW. The circulating- water, high-temperature
alarm system is usually combined with the
lubricating-oil, low-pressure alarm system (fig*
8-25) and consists of temperature-operated
switches (fig 8-3) located in the circulating
water lines of the engines* A rise in temperature
above a predetermined point causes the alarm
to sound.
GENERATOR AIR HIGH-
TEMPERATURE ALARM AND
THE GENERATOR BEARING HIGH-
TEMPERATURE ALARM SYSTEMS
LUBRICATING-OIL, LOW-
PRESSURE ALARM SYSTEM
The purpose of the lubricating-oil, low-
pressure alarm system, circuits 1EC and2EC,is
to sound an alarm whenever the pressure in the
lubricating-oil supply line to the main engine
and reduction gear, or to the turbine- driven or
diesel-driven generators, and other auxiliary
machinery falls below a predetermined minimum
limit. When the system is used for the main
engines, the circuit is designated 1EC; when
the system is used for either turbine-driven or
diesel-driven generators and other auxiliaries,
the circuit is designated 2EC. Both circuits
are energized from individual switches on the
local 1C switchboard which is located in the
appropriate engineroom,,
An EC circuit includes one or more pressure
type switches (fig. 8-2) installed in the lubricating-
oil lines of the associated equipment. The alarm
panel of the lubricating-oil, low-pressure alarm is
located near the operating control board of the
machinery on which the pressure switch is
installed.
The generator air high-temperature alarm
system, circuit 1ED, provides a means of indi-
cating high temperature of the cooling air exhaust
of generator sets rated at 500 kW and above.
The system consists of type IC/N thermostatic
switches, which energize visual and audible
signals whenever the temperature of the circu-
lating air rises above a predetermined limit.
The generator bearing high- temperature
alarm system, circuit EF, provides a means
of indicating high temperatures in the bearings
of generator sets of 200 kW and above. Thermo-
static switches energize visual and audible signals
when a bearing temperature rises above a pre-
determined limit.
SYSTEMS MAINTENANCE
As a rule the principles of operation of alarm
and warning systems are simple. However, be-
cause of the large number of systems installed
on most ships, this equipment will require a good
deal of attention from maintenance personnel.
157
SHIPBOARD ELECTRICAL SYSTEMS
PRESSURE
SWITCH
TYPE IC/N
THERMOSTATIC
SWITCH
POWER FROM
LOCAL I.C.
SWITCHBOARD
Figure 8- 25 --1C alarm circuits 1EC and 1EW.
27.38C
Maintenance should be accomplished as in-
structed by the applicable MRC's with attached
Equipment Guide Lists and manufacturer's tech-
nical manuals.
Operators, watchstanders, and maintenance
personnel should remember that when you use
test-cutout switches on the alarm panels and
switchboards to test an alarm circuit, only the
alarm indicators and associated visual and audible
signals will be testedo This type of test does not
verify that the sensing device employed in th
circuit will operate at the proper value, Th
sensing device could be, as is the case in al
too many instances, completely inoperable; ye
the circuit would test good from the alarm panel
A regular program should "be undertaken to teg
alarm circuits on a regular basis by duplicating
as closely as possible, the conditions which th
alarm system was designed to indicate. By doin
this, the entire system, including the sensin
device and its operating point, is verified*
CHAPTER 9
SHIP'S INDICATING, ORDER, AND
METERING SYSTEMS
The modern naval vessel is an extremely
complex machine. To properly operate a ship,
watch personnel require vast quantities of in-
formation relative to conditions within and without
the ship*
The Officer of the Deck must have a rapid
means of transmitting orders to the throttleman
and to the man on the helm, etc*, and just as
rapidly, he must know that his orders have been
received,. The actual speed and position of the ship,
the distance traveled, the speed of the main
engines, the wind speed and direction, the amount
of fuel remaining aboard, the salinity of the feed-
water, and a host of other information, are of
great interest to personnel throughout the ship.
Ship's Indicating, Order, and Metering Systems
measure and transmit much of this information
throughout the ship.
TANK LEVEL INDICATING
SYSTEMS
The tank level indicating system, circuit TK,
measures the amount of liquid in various ship-
board tanks and transmits that information,
electrically, to remote locations,,
A typical tank level indicator consists of
(1) a transmitter, which measures the liquid
level in a tank and converts that information to
an electrical signal; (2) a power supply; (3) an
indicator meter or meters, calibrated in gallons
or pounds of liquid; and, in some cases, (4) an
alarm circuit that warns of unusually high or
low liquid levels within the tank
Several different types of tank level indicating
systems^ whose transmitters employ different
principles of operation to detect liquid level, are
utilized aboard Navy ships. Of these systems the
type IC/MC, or GEMS, tank level indication
systems has proven to be one of the most
accurate and reliable
The GEMS tank level indicating system func-
tions essentially the same as the basic circuit
shown in figure 9-1. The movement of the float
causes the resistance of the voltage divider
network to vary In the circuit shown, the low
level is indicated when there is less voltage drop
between the contact points of the meter. A full
tank would be indicated when all of the voltage
drop across the resistor is being measured.
Instead of having the float connected mechan-
ically to the slider of a variable resistor as shown
in figure 9-1, the actual transmitter of the GEMS
system functions through magnetic mechanisms.
The transmitter consists of a waterproof tube.
Contained within the tube are many magnetically
operated reed switches and a voltage divider
network. A magnet is encapsulated within the
material of the float. As shown in figure 9-2,
the upward movement of the float and magnet
within the tube results in the operation of the
enclosed reed switches The reed switches are
connected to the voltage divider network in such
FLOAT
D.C. POWER
SUPPLY
TANK'
VOLTAGE
DIVIDER
RESISTANCE
Figure 9-1.
-Basic circuit for
indicator.
104.64
liquid level
159
v- TRANSMITTER
\ TUBE
\
SWITCHES
A & B CLOSED
MAGNETIC REED
SWITCHES
FLOAT
BAR
MAGNET
SWITCHES
A, B & C CLOSED
27.381
Figure 9-2. Operational sequence of magnetic
reed switches as float travels along transmitter
tube*
TRANSMITTER
(HOUSING VOLTAGE
DIVIDER)
PRIMARY
INDICATOR METER
AND D.C. POWER SUPI
TANK
SECONDARY I
INDICATOR
METER
I
a way that, as each reed switch closes for an
upward movement of the float, a quantity of
resistance will be added, thereby increasing
the voltage drop across the transmitter
As might be expected, there is a * 'stepping"
motion of the meter pointer as each quantity
of resistance is added to or subtracted from the
voltage dropping circuit. Since there are many
reed switches in proportion to the length of the
transmitter and since the change in the quantity
of resistance is small as each reed switch is
actuated, the "stepping" motion is barely dis-
cernible.
Figure 9-3 illustrates a typical GEMS liquid
level indicator system with primary and secondary
indicator meters.
The GEMS system can distinguish between two
liquids of different specific gravities, such as
fuel oil and water, when a float material is used
that will float in the denser liquid but not in the
less dense. Transmitters with this type float
are used in compensated fuel oil tanks to dis-
tinguish between the fuel and water and indicate
only how much fuel remains.
SAFETY
When maintenance is being performed on any
tank level indicating system, and a tank will be
Figure 9-3. Diagram of a GEMS liqu:
indicator system.
entered, be sure that the Gas Free I
has tested the tank before maintenance p*
enter. Follow all safety directives pr
SALINITY INDICATOR
SYSTEM
The salinity indicator system, cir<
indicates the amount of salinity in water
aboard ship. The system is a necessity
ship because all freshwater, when unde
made from seawater Excessive salinit
boiler feedwater causes pitting of tt
and rapid deterioration due to elecl
Salinity indicators are usually provide
enginerooms and the firerooins to ct
condensate from the main and auxilia
denserso The indicators are also provide
evaporator plants to indicate the degree <
of the water at various selected point
distilling system*
The salinity indicator system operate
principle that an increase of the ele<
impurities (principally salt) in water ir
the electrical conductivity of the watei
electrodes are immersed in the wate
tested and a stable alternating voltage i*
160
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
across the electrodes, a stable alternating cur rent
will flow through the water if the impurity content
and the temperature of the water remain un-
changed.
The amount of current flow is indicated on a
meter whose scale is graduated in chloride equiv-
alent parts per million. If the saline content of
the water increases because salt water is leaking
into the system or because of faulty operation of
the distilling plant, the conductivity between
the electrodes increases, and the meter reading
increases by an amount proportional to the
increase in salinity.
A complete salinity indicator system consists
of one or more salinity cells which contain
the electrodes, a salinity indicator panel which
contains the meter, power supplies, control
equipment, and, in some cases, alarm circuitry
which warns of unusually high salinity conditions.
SALINITY CELL
The salinity cell (fig. 9-4) consists mainly
of a 3-conductor interconnecting cable, packing
nut, cell body, electrode assembly, and an auto-
matic temperature-compensating resistor housed
within the cell body.
The packing nut and cell body properly support
the electrode assembly in the ship's piping
system and, along with the cell valve (discussed
"below), form a watertight seal. They also provide
a means of inserting and removing the cell from
the ship's piping systems without loss of liquid.
The electrode assembly consists of an inner
electrode, outer electrode, and the automatic
temperature compensating resistor. . The inner
electrode consists of a platinum-plated button
placed on the end of the cell body but insulated
from it. The outer electrode is a platinum -plated
cylinder that is connected to the cell body and
surrounds the inner electrode. The outer electrode
is pierced with holes to vent any gases trapped
between the two electrodes and to permit free
circulation of water over the electrodes.
Two factors actually control the conductivity
of the impure water. The firstf actor, the salinity,
has been discussed. The second factor is the
temperature of the solution. As the temperature
of a saline solution increases, its conductivity
decreases. This phenomenon causes the salinity
system to indicate an impurity level that is less
than that actually present. To compensate for this
action, an automatic temperature-compensating
resistor is placed inside the cell body. By its
location within the cell, the automatic
temperature-compensating resistor maintains its
temperature at that of the surrounding water .The
resistor's conductance varies by a factor that is
proportional to diluted seawater. Since both the
resistor and the diluted seawater are affected
by temperature in a like manner, the resistor
is connected in the circuit so that the net result
of a temperature change is zero. In this way,
the salinity equipment continually indicates the
actual impurity content through a temperature
range of 40 F to 250 F.
PACKING NUT
OUTER ELECTRODE
INNER
ELECTRODE
ELECTRODE
ASSEMBLY
7.1 SOX
Figure 9-4. Salinity indicator cell.
161
SHIPBOARD ELECTRICAL SYSTEMS
CELL VALVE
As stated earlier, the cell valve, in conjunction
with the packing nut and cell body, provides the
means to insert or retract the cell from the
ship's piping systems without loss of water
while maintenance is being performed. Figure'
9-5 provides a view of a salinity cell installed
in a ship's piping system through a cell valve.
SALINITY INDICATOR
PANEL
As previously stated, a salinity indicator
panel measures the conductivity of the water
being tested by the salinity cell and displays
this information as a reading on a meter. In
some cases the indicator panel provides audible
and visual alarms if the salinity of the water
under test exceeds specified limits. There are
many different types of salinity indicator panels
available; two are discussed below.
IC/E1U-S3 Salinity
Indicator Panel
The IC/E1U-S3 salinity indicator panel (fig.
9-6) monitors the conductivity of one salinity
cell continuously. This panel may be used in
a system that contains only one salinity cell
such as an electronics cooling water system,
or it may be used in a larger system where
a continuous reading of one particular cell
NIPPLE
PACKING
CELL
BODY
27.382
Figure 9-5. -Salinity cell installation.
27.383
Figure 9-6. IC/E1U-S3 indicator panel.
of a system is desirable,. The unit contains
a meter, a test pushbutton, calibration resistor
network, and an isolation transformer.
The test pushbutton and calibration network
serve as a self-check circuit. This self-check
circuit serves only to test the meter's accuracy,
When the test pushbutton is depressed the meter
should read 1.7 ppm. If it doe snot, the calibration
resistor contained within the unit should be
162
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
adjusted by maintenance personnel for this
reading.
As the electrodes of each salinity cell are
immersed in water f leakage current may flow
from the electrodes through piping to the ship's
hull (ground). In fact, the outer electrode of the
salinity cell makes actual metallic contact with
the cell body and packing nut. When the cell
is installed in a ship's piping system, a very
low resistance path is provided for the 115 VAC
applied to the outer electrode to ground. The
isolation transformer of the unit isolates the
ground paths provided by the salinity cells from
the ship's supply voltages. In addition, it does
not allow the ground paths of one cell to affect
the reading of another cell, and it reduces the
electrical shock hazards for personnel associated
with this system*
IC/D5RM Salinity
Indicator Panel
The IC/D5RM salinity indicator panel (fig.
9-7), is designed to monitor five salinity cells
of a distilling plant, although it may be used
in a condensate system. The panel has an alarm
system to warn of high salinity conditions and
circuitry to control a solenoid trip valve winch
is used to dump the distillate coming from the
plant in the event its salinity exceeds a specified
amount. The panel is modular in construction
and contains a power unit, a meter unit, a valve
position and meter test module, a relay module,
and five identical salinity modules.
Please refer to figure 9-7 as we discuss the
IC/D5RM salinity indicator panel in the succeeding
paragraphs.
SILENCE
SWITCH
VALVE POSITION
8 METER TEST
MODULE
RELAY MODULE
SALINITY
MODULE
METER SWITCH
Figure 9-7.- IC/D5RM salinity indicator panel.
163
7.151
SHIPBOARD ELECTRICAL SYSTEMS
The power unit has a white power-on indicator
lamp and two indicating fuse holders. Contained
within the unit is a transformer which provides
power to operate the salinity module sand salinity
cells. The transformer also isolates the grounds
inherent to the salinity cells, as discussed earlier.
The salinity modules, of which there are five,
continuously monitor the salinity cell connected
to it. If its alarm set point is exceeded, the module
signals by flashing its red indicator light and by
sounding an external audible signal that is common
to all five module s e
A high salinity condition is indicated initially
by a flashing red indicator light and an external
audible alarm. To clear the external alarm for
other incoming alarms, the silencing switch on
the module is placed in the SILENCE (down)
position, causing the red indicator light to glow
steadily. When the high salinity condition is
corrected, the red light again begins to flash to
remind the operator to return the silencing
switch to the NORMAL (up) position.
The 3-position, spring-loaded meter switch
has a NORMAL (center) position, a TEST position,
and a METER position. When placed in the TEST
position, the meter switch causes the cell to
behave as though a high salinity condition exists
energizes the alarm circuit causing the red
alarm light to flash and the alarm relay to sound
the external alarm. The meter switch, when
placed in the METER position, connects the
meter unit to the associated salinity cell, and
a salinity reading is indicated on the meter.
The relay module contains an external alarm
relay and a 2-second delay relay. The external
alarm relay is controlled by the salinity modules.
With the silence switch in the NORMAL position,
an alarm condition in any one of the salinity
modules will cause the external alarm relay
contacts to close, sounding the external audible
alarm. The 2-second delay relay is used in
conjunction with the solenoid trip valve. Any
one of the five salinity modules may be used to
actuate the time delay relay. Usually, the wiring
inside the panel is connected so that the salinity
module that monitors the distillate, after it has
passed through the final stages of the distilling
plant, is selected to control the time delay
relay. If an alarm condition lasts for more than
2 seconds, in the selected module, the 2-second
time delay relay causes the solenoid trip valve
to be deenergized (tripped) . The tripping of the
solenoid trip valve causes the distillate to be
dumped to the bilges or overboard. When the
alarm condition is cleared, the solenoid trip
valve must be manually reset. A 2-second delay
relay is used so that spurious alarms in the
selected module will not trip the solenoid valve.
The valve position and meter test module
has a green valve position indicator lamp and a
meter test switch. The dual purpose of the
unit is to indicate whether the solenoid trip
valve is in the NORMAL or TRIPPED position
and to provide a means of testing the meter
unit.
When the solenoid trip valve is in the NORMAL
position, the green indicator lamp is illuminated
steadily; when in the ABNORMAL position, the
green alarm light flashes; and when the valve
is reset manually, the green alarm light is
again lighted steadily.
The meter test switch, when placed in the
TEST position, connects the meter unit to a
circuit which simulates a known salinity con-
dition (1.7 ppm) to check the calibration of the
meter.
SAFETY
As previously discussed, dangerous potentials
are present on all the surfaces of the salinity
cells. The ENTIRE SYSTEM should be deenergized
and RED-TAGGED when any maintenance is
performed on the salinity cells or inside the
salinity panel. Also, personnel should be cautioned
prior to working on salinity cells to take adequate
precautions to avoid injury from hot pipes, steam
and/or high pressures which may be present in
the ship's piping systems.
RUDDER ORDER AND
RUDDER ANGLE
INDICATOR SYSTEMS
The rudder order system (circuit L) and the
rudder angle indicator system (circuit N) utilize
synchros, as do many other 1C circuits, to
transmit information. Synchros are electromag-
netic devices which are used primarily to transmit
angular position data. Physically, as shown in
figure 9-8A, a synchro resembles a small electric
motor, butfunctions as a transformer, the primary
of which is connected to the shaft whose angular
position is to be transmitted. The secondary of the
synchro surrounds the primary of the synchro.
When an a.c. voltage is applied to the primary,
its angular position in respect to the secondary
determines the voltage induced in the secondary
Each time the angular relationship between the
synchro's primary (rotor) and secondary (stator)
164
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
BALL
BEARING
STATOR AND
SECONDARY WINDINGS
SLIP RINGS
ROTOR AND
PRIMARY WINDINGS
CUTAWAY VIEW OF SYNCHRO
SYNCHRO
TRANSMITTER
INTERCONNECTING
LEADS
HANDWHEEL
115 VOLT
SUPPLY
RECEIVER
INDICATOR
DIAL
B SIMPLE SYNCHRO SYSTEM
Figure 9-8 e Synchros.
236.399
is changed, the induced voltages in the stator
change.
Figure 9-8B shows a simple synchro system *
Tlie rotor of the transmitter and the rotor of the
receiver are connected to the a.c. supply voltage.
The stator of the receiver is connected to the
stator of the transmitter. When the handwheel
in figure 9-8B is turned, the rotor-stator angular
positions of the transmitter and the receiver are
no longer the same, the voltages induced in their
respective stators will not be the same These
two different stator voltages result in an un-
balanced condition between the transmitter and
receiver. As a result of this unbalance, a torque
is produced electro-magnetically between the
rotors and the stators of the transmitter and
the receiver. The rotor of the transmitter is held
in position which causes the receiver's rotor to
move to a position to eliminate the unbalanced
165
SHIPBOARD ELECTRICAL SYSTEMS
condition. As a result, the movements of the rotor
of the transmitter are followed by the rotor
of the receiver. The above information is a very
simple explanation of synchro principles. Detailed
information concerning the operation and main-
tenance of synchros is contained in Basic Elec-
tricity, NAVPERS 10086, Synchros, Servo, and
Gyro Fundamentals, NAVPERS 10105, and
Military Standardization Handbook for Synchros,
MIL Hdbk 225-(AS).
RUDDER ORDER SYSTEM
Under normal conditions the rudder of a ship
is controlled remotely from the helm on the bridge.
If the remote steering control system should fail,
the rudder order system (circuit L) electrically
transmits rudder orders to the steering gear
room where watch personnel can control the
steering gear.
The two major units of the rudder order
system serve a dual purpose in that components
of both units are used in conjunction with the
rudder angle indication system (circuit N).
The rudder order transmitter-rudder angle
indicator (fig. 9-9) is installed on the bridge
to transmit the ordered rudder angle to watch
personnel in the steering gear room. This indi-
cator contains a synchro receiver, which is a
component of the rudder angle indicating system
(circuit N), and a synchro transmitter, which
is a component of circuit L.
PUSHSWITCH
The rudder order-rudder angle indicator (fi
9-10) , installed in the steering gear room , contaii
two synchro receivers. One of the receivers
used in conjunction with the rudder indicatii
system (circuit N). The other receiver, a con
ponent of circuit L, receives the transmit!*
order from the bridge unit.
The control knob on the rudder ord<
transmitter- rudder angle indicator (fig. 9-
manually positions the pointer marked ORD i
well as the rotor of the synchro transmitter
the bridge unit. The transmitter produces a sign
which is sent to the circuit L receiver in ti
steering gear room. The signal causes the point*
(ORD) on the receiver to move automatically
a position that corresponds to the position of ti
pointer on the bridge.
The pushswitch in figure 9-9 is used j
conjunction with a bell in the steering* gear roon
Each time a new rudder order is transimtte<
the pushswitch is depressed to alert steeric
gear watch personnel to the new order.
7.126.1
Figure 9-9. Rudder order transmitter-rudder
angle indicator.
7.126.5
Figure 9-10. Rudder order -rudder angle
indicator.
166
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
RUDDER ANGLE
INDICATOR SYSTEM
The rudder angle indicator system (circuit N)
electrically transmits the actual angular position
of the ship ' s rudder to de signated stations through-
out the
The rudder angle transmitter (fig d 9-11)
consists of a synchro transmitter mechanically
linked to the rudder stock in such a manner
that the synchro transmitter shaft follows the
movement of the rudder. It transmits rudder
angle data to various ship's indicators,,
The rudder angle indicator (fig 9-12) consists
of a fixed dial and a pointer mounted on the
shaft of a synchro receiver* The synchro receiver
positions the pointer on the dial face in response
to the transmitted rudder angle.
The angular position of the rudder is also
transmitted to the receivers associated with
circuit N in the units shown in figures 9-9 and
9-10*
Figure 9-13 is a block diagram of the rudder
order and rudder angle indicating systems, show-
ing the various units as discussedo
The combination rudder order transmitter-
rudder angle indicator, as well as many other
indicators and components, is mounted in a
steering control console (fig. 9-14) on new con-
struction ships, The console contains much of
7.126.6
Figure 9-1 2. Rudder angle indicator (circuit N).
the information and controls required for a
helmsmano
PROPELLER REVOLUTION
INDICATOR SYSTEM
7.129
Figure 9-ll Rudder angle transmitter.
The propeller revolution indicator system
(circuit K) indicates instantaneously and con-
tinuously the (1) revolutions per minute, (2)
direction of rotation, and (3) total revolutions
of the individual propeller shafts . The information
is indicated in the enginerooms, pilothouse, and
other required locations*
The propeller revolution indicator system
usually consists of two different types of equip-
ment: (1) synchro- type equipment and (2) magneto-
voltmeter type equipment. The synchro-type
equipment is installed in large combatant ships
and in many newly constructed small ships.
The magneto- voltmeter type equipment is less
complicated and is installed in small ships.
167
SHIPBOARD ELECTRICAL SYSTEMS
PUSHSWITCH
O
RUDDER ORDER TRANSMITTER-
RUDDER ANGLE INDICATOR
BRIDGE
CIRCUIT N
' INFORMATION
TO VARIOUS RUDDER ANGLE
INDICATORS
STEERING GEAR EQUIPMENT
RUDDER ORDER -
RUDDER ANGLE INDICATOR
CIRCUIT L
"INFORMATION
ROOM
STEERING RAM ROOM
Figure 9-13. Block diagram of basic rudder order-rudder angle indicating system.
27.2
SYNCHRO-TYPE
EQUIPMENT
A representative synchro-type propeller revo-
lution indicator system installed aboard a DDG
as illustrated by the block diagram in figure
9-15. The system consists of two transmitters,
two indicator-transmitters, and four indicators.
The transmitters are driven by the main engines
and are electrically connected to indicator-
transmitters at their respective throttle stations.
Indicators, such as those in figure 9-16, are a
installed on the gage boards in both engineroc
and in the pilothouses. Each indicator has
backing signal lamp which, when lighted, dene
astern rotation of the propeller shaft.
A synchro signal representing and proportic
to the rotary motions of the propeller si
is transmitted by the transmitter (fig. 9-1
to the associated indicator-transmitter (:
9-16B), which continuously indicates the tc
168
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
RUDDER ORDER TRANSMITTER-
RUDDER ANGLE INDICATOR
REMOTE IMD. WAG. COMPASS
REPEATER
SHIPS COURSE
INDICATOR
GRAB BARS
HELM AIMGLE
INDICATOR
STEERING
CONTROL
"POWER ON"
INDICATOR
LIGHTS
RUDDER ORDER TRANSMITTER
OPERATING KNOB
EMERGENCY STEERING SWITCH
RUDDER ORDER ATTENTION
PUSHSW1TCH
MASTER DIMMER CONTROL
RUDDER ORDER TRANSMITTER
"POWER ON" PILOT LIGHT
COURSE TO STEER
INDICATOR
STEERING WHEEL
DOOR FOR ACCESS
TO TERMINAL
BOARDS FOR
SHIPS WIRING
7.133
Figure 9-1 4 Steering control console,,
revolutions of the propeller shaft on a counter
and converts the received synchro signal into
an angular indication of RPM. The RPM reading
is also transmitted to indicators via a synchro
transmitter contained within the indicator-
transmitter o
The indicator (fig. 9-16C), repeats the rpm
reading received from the associated indicator-
transmitter. The entire system operates on the
ship's single-phase, 11 5- volt, 60-hertz power
supply.
MAGNETO- VOLTMETER
TYPE
The magneto- voltmeter propeller revolution
indicating equipment consists of a magneto-type
transmitter geared to each propeller shaft and
electrically connected to remotely located indica-
tors which consist of a voltmeter calibrated in
revolutions per minute.
The magneto is a permanent magnet type
d.c. generator which is driven at a speed pro-
portional to that of the propeller shaft.
169
SHIPBOARD ELECTRICAL SYSTEMS
Figure 9-15, Block diagram of propeller revolution indicator system.
27.335
The indicators receive this voltage and indicate
on the voltmeter scale the rpm of the propeller
shaft. A total revolutions counter registers the
total number of propeller revolutions locally
at the magneto transmitter unit and a synchro
transmitter transmits these revolutions to a
synchro receiver which drives the associated
total revolutions counter in the remote indicator.
and wind direction and speed indicator. Usually
two wind direction and speed detectors are
mounted on the foremast, one on the port side
and one on the starboard side,, The wind direction
and speed transmitter is installed in the 1C
room. The wind direction and speed indicators
are installed in various spaces as required by the
type of ship*
WIND DIRECTION AND
SPEED INDICATOR
SYSTEM
The wind direction (circuit HD) and speed
(circuit HE) indicator system, indicates instan-
taneously and continuously the (1) wind direction
in degrees relative to the ship's heading, and
(2) wind speed in knots relative to the ship.
The type-B wind direction and speed indicator
system consists of a wind direction and speed
detector, wind direction and speed transmitter,
WIND DIRECTION AND
SPEED DETECTOR
The wind direction and speed detector (fig.
9-17) consists of a thin-gage Monel metal housing
formed into a streamlined wind vane with a
relatively large tail surface mounted on a vertical
support assembly. The rotor assembly, attached
to the head of the vane is held directly into
the wind by the vane assembly and converts
the wind speed into rotary motion. The speed
of rotation of the rotor assembly is proportional
to the velocity of the wind striking the rotor
blade s
170
TRANSMITTER
A
INDICATOR -TRANSMITTER
B
INDICATOR
c
Figure 9-16. Propeller revolution indicating equipment.
7.126.7
The direction synchro transmitter, mounted
in the vertical support assembly, is directly
coupled to the vane so that when the wind positions
the vane, the synchro transmitter rotor is dis-
placed the same angular amount. The angular
positions are transmitted electrically to a synchro
control transformer in the wind direction sub-
assembly of the transmitter (fig. 9-18). Because
wind directions are indicated in relative bearings,
the direction synchro transmitter in the detector
is set to transmit zero when the rotor assembly
of the detector unit points to the bow of the ship*
The speed synchro transmitter, mounted in
the head of the vane, is coupled through gears
to the rotor assembly. The reduced rotary
motions are transmitted electrically to a synchro
receiver in the wind speed subassembly of the
transmitter unit (fig. 9-18).
The mbunting and the vertical support assem-
blies of the wind direction and speed detector are
171
SHIPBOARD ELECTRICAL SYSTEMS
ROTOR
PLATE
BEARING
FLANGE
ROTOR
ASSEMBLY
INNER
HUB
HOUSING
CENTER WANE
SUPPORT ASSEMBLY
ROTOR
SHAFT
VANE
SHAFT
ASSEMBLY
COLLECTOR
RING
ASSEMBLY
^VERTICAL
SUPPORT
ASSEMBLY
MOUNTING
ASSEMBLY
"STERN
PIPE
FITTING
FOR
TERMINAL
TUBE
EXTERNAL VIEW
INTERNAL VIEW
B
7,145
Figure 9-17. Wind direction and speed detector.
172
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
WIND DIRECTION 8
SPEED DETECTOR
WIND DIRECTION a
SPEED INDICATOR
r
\
DIRECTION
SYNCHRO
TRANS.
DIRECTION
SYNCHRO
TRANSMITTER
CT }- --) [ TX
WIND DIRECTION SUBASSEMBLY
SHADED-POLE
, FOLLOWUP
MOTOR
SYNCHRONOUS
MOTOR '
REFERENCE
VOLTAGE
SPEED
SYNCHRO
. RECEIVER
( T R V-
SPEED
SYNCHRO
TRANSMITTER
WIND SPEED SUBASSEMBLY
| WIND DIRECTION AND SPEED TRANSMITTER
Figure 9-18. Block diagram of type-B wind direction and speed indicator system .
provided with flanges for bolting the two sections
together.
WIND DIRECTION AND
SPEED TRANSMITTER
The wind direction and speed transmitter
(fig. 9-18) consists of a wind direction sub-
assembly and a wind speed subassembly mounted
on individual baseplates to form a complete
unit enclosed in a metal case designed for
bulkhead mounting.
Wind Direction Subassembly
The wind direction subassembly is essentially
a servo unit comprised of a synchro control
transformer, followup amplifier, followup motor,
and synchro transmitter.
Please refer to figure 9-18 as we continue
our discussion.
When the rotor of the wind direction synchro
(CX) located in the wind speed and direction
detector, and the rotor of the synchro control
transformer (CT), located in the wind direction
subassembly, are in correspondence, the output
voltage from the synchro control transformer
will be zero. When a change in wind direction
causes the vane of the wind speed and direction
detector to change its position, the direction
synchro transmitter and the synchro control
transformer rotors will no longer be in cor-
respondence and a voltage is induced in the
rotor of the synchro control transformer. The
output voltage from the rotor of the synchro
control transformer is either in phase or 180
out of phase with the source (reference) voltage,
depending on the direction in which the vane
has turned. Thus, the phase of the output of
the control transformer reverses with respect
to the reference voltage as the direction of
displacement reverses. The magnitude of the
output voltage from the synchro control trans-
173
SHIPBOARD ELECTRICAL SYSTEMS
former represents the amount by which the
shafts of the synchro control transformer and
the direction synchro transmitter are out of
correspondence,, Thus, the direction in which
the transmitter shaft is turned determines the
phase of the output voltage from the synchro
control transformer with respect to the reference
voltage, and the amount of displacement deter-
mines the magnitude of the output voltage from
the synchro control transformer.
The synchro control transformer voltage,
caused by the angular displacement, is amplified
and fed to the followup motor which drives the
synchro transmitter and control transformer
through gears into correspondence with the
synchro transmitter in the vane. The direction
in which the followup motor drives is determined
by the phase of the output voltage from the
synchro control transformer; the speed at which
the followup motor drives is determined by the
magnitude of the output voltage from the synchro
control transformer. The synchro transmitter
located in the wind direction subassembly trans-
mits an angular displacement representing wind
direction to the synchro receiver sin the remote!
located indicators.
Wind Speed Subassembly
The wind speed subassembly (fig. 9-19) utilize
a friction disk and roller integrator to convei
the rotary motion produced by wind velocit
to an angular quantity that may be displaye
on a dial. The subassembly receives the rotax
motion from the speed synchro transmitter c
the detector. The rotary motion, which represent
wind velocity, is converted into an angula
displacement by the friction disk and rolle:
integrator assembly. The mechanical output o
the integrator positions the rotor of the synchro
transmitter which transmits an angular displace-
ment signal representing wind velocity to thi
various indicators throughout the ship.
WIND SPEED AND
DIRECTION INDICATOR
The wind direction and speed indicator (fig,
9-20) is a dual unit consisting of a wind direction
WIND DIRECTION
AND SPEED DETECTOR
I 1
SPEED SYNCHRO
TRANSMITTER
j !
I WIND SPEED I
I INDICATOR I
I
CONSTANT SPEED
REDUCTION (SYNCHRONOUS)
GEAR MOTOR
ASSEMBLY
I ^ 1 SYNCHRO
TRANSMITTER
PINION
REDUCTION
GEAR
ASSEMBLY
CIRCULAR
^ --- , RACK
WORM
GEAR
SPIRAL
GEAR
DISK DRIVING
DRIVE DISKS
GEARS
ROLLER GEAR ASSEMBLY -
GEARS
Figure 9-19. Wind speed subassembly,
174
7.147
Chapter 9 -SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
UNDERWATER LOG AND
DUMMY LOG SYSTEMS
The underwater log system (circuit Y) meas-
ures and indicates the speed of the ship through
water and the distance traveled through the
water. It transmits these indications to the
various speed indicators, distance indicators,
and weapons and navigational systems, as re-
quired.
The dummy log system (circuit 4Y) produces
simulated speed and distance signals for the
various ship's systems that require either ship's
speed or distance inputs. The system serves two
purposes (1) to simulate ship's movement
through the water in order to train personnel and
align equipment and (2) to serve as a backup for
the underwater log system. The dummy log may
be used to supply an estimated speed and distance
signal to ship's systems in case the underwater
log system becomes inoperable.
In actual practice aboard ship, circuits Y
and 4Y are usually tied together by a switching
arrangement that permits information pertaining
to the ship's speed and distance from either
source to be fed throughout the ship to a common
set of indicators and equipment.
7.148
Figure 9-20. Wind direction and speed indicator.
subassembly and a wind speed subassembly. The
two subassemblies are identical except for the
dials. Each consists of a synchro receiver which
indicates on a fixed dial by means of a revolving
pointer attached directly to its shaft. The sub-
assemblies are mounted on individual baseplates
and enclosed in a metal housing to form a
complete wind direction and speed indicator
unit.
SAFETY
The maintenance of the wind speed and direc-
tion indicating system, as well as other equipment
under the cognizance of E division, requires that
personnel work aloft at one time or another. The
regulations for men working aloft contained in
Navy Safety Precautions For Forces Afloat,
OPNAV Instruction 5100.19, and in ship's in-
structions, must be followed for these operations.
Personnel who are to work aloft should be
thoroughly familiar with all regulations and
safety precautions concerned.
UNDERWATER LOG
SYSTEM
The majority of all current underwater log
systems employ the electromagnetic principle
to sense the ship's speed through the water.
Several different configurations employing this
principle of operation have been produced by
various manufacturers for the Navy.
Electromagnetic Principle
The electromagnetic principle used in the
underwater log system is the same basic principle
by which a generator produces a voltage. If a
conductor is moved through a magnetic field, a
voltage will be induced in the conductor. The
magnitude of the induced voltage will vary with
the number of active conductors moving through
the magnetic field, the strength of the magnetic
field, and the speed at which the conductor is
moved through the magnetic field. An increase
in the number of conductors, the strength of
the magnetic field, or the speed of the conductor
through the field will result in an increase in
induced voltage.
175
SHIPBOARD ELECTRICAL SYSTEMS
The electromagnetic underwater log functions
by placing a magnetic field in seawater. Seawater
conducts electricity very well and is used as
the conductor. When the ship is not moving through
the water, there is no relative motion between
the magnetic field and the conductor; therefore,
no voltage is induced in the conductor (seawater).
As the ship begins to move, relative motion takes
place and a voltage is induced in the seawater.
An increase in the ship's speed increases the
induced voltage directly proportional to the in-
crease in ship's speed By comparing the induced
voltage to a known voltage, an accurate determi-
nation of the ship's speed can be made*
Sea Valve and
Rodmeter Assemblies
Mounted in the hull of the ship, the sea valve
and packing assembly (fig. 9-21 and 9-22) provide
a watertight support for the rodmeter, enabling
the rodmeter to be retracted or extended through
the open sea valve,, The sea valve, when closed
also seals the hull when the rodmeter is retracted.
JUNCTION BOX
PACKING
RODMETER
VALVE BODY
Figure 9-21. Sea valve.
27.271
SHIP'S HULL
140.159
Figure 9-22. Exploded view of the sea valve and
packing assembly with rodmeter installed.
The rodmeter (fig. 9- 23) is made of corrosion-
resistant Monel metal and is available in different
lengths. The main components of the rodmeter are
the rod weldment, the junction box, and the
sensing unit.
The rod weldment makes up most of the
length of the rodmeter< It is a hydrofoil cross
section, nickel-copper, watertight tube. The
sensing unit is cemented to the lower end of
the rod weldment, and the junction box is bolted
to the upper end. Two shielded electrical cables
connected to the sensing unit pass through the
rod weldment and terminate in the cable con-
nectors.
The sensing unit (fig. 9-24) is a plastic molding
(boot) made of an epoxy resin mixed with glass
fiber a In it are imbedded a coil and two Monel
metal buttons.
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
JUNCTION BOX
COVER
CABLE
CONNECTORS
-ROD
WELDMENT
SPEED SIGNAL
TO INDICATOR
TRANSMITTER
SENSING UNIT
OF RODMETER
SUPPLY
FROM
INDICATOR
TRANSMITTER
INDUCED EMF
APPEARS ACROSS
PICKUP BUTTONS
\
<^
&
INDUCED VOLTAGE CIRCUIT
IN PLANE OF WATER
DIRECTION OF
SHIP'S MOVEMENT
SENSING
UNIT
PICKUP
BUTTON
Figure 9-23 c Rodmeter.
27.272
The .coil of the sensing unit is excited with
a 60-hertz a.c. voltage, thus creating a magnetic
field in the seawater around the rodineter sensing
unit*
As the ship and magnetic field move, the
water on both sides of the rodineter is cut by
lines of flux, and a voltage proportional to the
27.273
Figure 9-24. Cutaway view of sensing unit.
velocity of the water is generated on both sides
of the rodineter. The pickup buttons located
on each side of the rodmeter make contact
with the water and pick up the voltage being
generated in the water. This voltage (propor-
tional to the ship's speed through the water)
is applied to the indicator-transmitter (discussed
later) where the actual ship's speed and distance
are calculated,,
Fixed Rodmeter
The fixed rodmeter is installed on nuclear
submarines and new construction surface craft.
It replaces the sea valve and rodmeter assem-
blies discussed above. As shown in figure 9-25,
the rodmeter is mounted through the hull of the
ship with the sensing element exterior to the
hull and the electrical connection inside the
ship* The sensing unit of the rodmeter is basically
the same as that of the previously discussed
rodmeter. The major advantage of the fixed
rodmeter installation is the increased water-
tight integrity of the hull.
177
SHIPBOARD ELECTRICAL SYSTEMS
-"0" RINGS
STOP
SIDE SCREW
W/"0" RING
HULL
RETAINING
RING
SENSING
UNIT
FORWARD
VIEW
PORT
VIEW
Figure 9-25. Fixed rodmeter.
27.385
NOTE: Seawater dools the rodmeter and pre-
vents the sensing element from overheating
when the system is operating. To prevent pos-
sible damage to the sensing element of the
rodmeter the underwater log equipment should
never be energized unless the sensing element
is emersed in water.
Indicator- Transmitter
The indicator-transmitter contains all the
electrical and mechanical components necessary
to measure the voltage from the rodmeter and
to convert it into ship's speed and distance
signals.
Two underwater log systems (the Litton
Indicator -Transmitter and the Chesapeake
Indicator-Transmitter) will be discussed below,
The rodmeters of both systems are interchange-
able. The type shown in either figure 9-23
or 9-25 may be used. The construction of the
indicator-transmitters is the most distinctive
difference between the two systems.
LITTON INDICATOR-TRANSMITTER. -The
Litton indicator-transmitter (fig. 9-26) is the
178
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
DISTANCE
MILES
COUNTER
DUMMY SIGNAL
UNIT
DISTANCE SERVO
MOTOR
SPEED DIAL
SPEED SERVO-'] \ ^
MOTOR nj|
^
MECHANICAL
UNIT
ASSEMBLY
CASE
ELECTRONIC
UNIT
ASSEMBLY
ACCESS COVER
FOR WIRING
Figure 9-26.- Litton indicator-transmitter (cover removed) .
7.153
older in design of the two units. It has been
installed in Navy ships for approximately 20
years,,
The Litton underwater log system is com-
prised of the components shown in figure 9-27.
The system functions as follows: The rodmeter
produces an a.c. signal voltage proportional
;0 the ship's speed. This signal is amplified and
ed to the speed servomotor, which drives
the speed synchro transmitter, the dual-pointer
dial, and the integrator. The integrator converts
the input from the speed servo into a distance-
traveled output which drives a synchro-
transmitter and a 6-drum counter to display
distance traveled in nautical miles. A dummy
signal circuit (not shown) performs no function
in normal equipment operation but provides
simulated signals that can be used in checking
the functioning of the system .
SHIPBOARD ELECTRICAL SYSTEMS
ELECTRICAL SIGNAL
,A^
MECHANICAL LINKAGE
40K/360 60HZ
SPEED
SIGNAL
TO SHIP'S "^
WIRING
INPUT
TRANSFORMER
j\ SPEED
71 SIGNAL
l
DISTANCE
SYNCHRO
TRANSMITTER
y CONSTANT
^SPEED
MOTOR
INDICATOR-TRANSMITTER
I
Figure 9- 27. Block diagram of Litton Underwater Log System.
27.27'
Refer again to figure 9-27. The input trans-
former functions as an error detector. It receives
the speed voltage generated by the rodmeter
and a response signal which is a measured
voltage that represents the present position
of the response potentiometer.
When the response potentiometer is properly
positioned, the response signal cancels out the
speed signal in the input transformer and there-
fore the error signal (output signal) from the
input transformer will be zero. When the speed
signal and the response signal are not of the
same magnitude, an error signal is produced by
the input transformer. The error signal is
magnified by the servoamplifier until it is of
sufficient magnitude to drive the speed servo-
motor. The speed servomotor drives the dial,
speed synchro transmitters, integrator, and the
response potentiometer in accordance with the
error signal through gearing until the response
signal again equals the speed signal. For any
change in speed, an error signal is developed
which causes the servomotor to drive the gear
train until the signal from the response po
tentiometer again equals the speed signal,,
In this manner, the indicator-transmitte:
continuously indicates ship's speed on the dial
and the speed synchro transmits ship's speed t
the various ship's repeaters.
The integrator is used in the indicator-
transmitter to change an angular displacemen
into a rotary motion The roller is positionei
on the disk of the integrator by the speei
servomotor. The position of the roller represent!
ship's speed. The position nearest the cente:
represents zero ship's speed, while a positioi
near the edge represents 40 knots. Dependini
on ship's speed, the roller of the integrate]
is driven by the disk at a speed that represents
ship's distance traveled. The integrator outpu
is used to drive a miles counter and a synchrc
transmitter which transmits a corresponding
signal to remote receivers. However, because
a direct load on the integrator output will likely
cause the roller to slip, a distance servo has
180
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
been inserted between the integrator and its
load. The distance servo is used to drive the
counter and distance synchro transmitter. In
this way the integrator is mechanically isolated
from its load.
The dummy signal circuit (not to be confused
with the dummy log system) produces voltage
signals which simulate speed outputs from the
rodmeter. Such signals can be used to check
the performance of the speed and distance servos.
The dummy signal circuit provides a simulated
speed signal that causes the speed servo to
stabilize at any of four dial readings (0, 5 t
15, or 30 knots) and permits measurement of
the accuracy of distance servo and integrator
functioning. The dummy signals are not intended
for calibration purposes; they only check the
functioning of the equipment, and proper operation
of the equipment with dummy signals does not
necessarily mean that it will properly measure
and indicate ship's speed through the water,
CHESAPEAKE INDICATOR-
TRANSMITTER. The Chesapeake indicator-
transmitter (fig. 9-28) uses solid state devices
REMOTE CONTROL
UNIT
INDICATOR-
TRANSMITTER
ROOMETER
140.158
Figure 9-28. Major components of the Chesapeake
Underwater Log System.
and its circuits reflect changes in the state
of the art that took place between the development
of the Litton and the development of the Chesa-
peake* As you can see in figure 9-29 f the basic
principles of operation in the two are very
similar The principal differences between the
two are that the Chesapeake unit: can supply
five different synchro speed output signals; has the
dummy log system {circuit 4Y) incorporated
into its circuitry; uses logic circuits in the
speed servoamplifier; and uses a solid state
integrator, which also uses logic circuits, instead
of the mechanical integrator of the Litton
unit.
In operation the speed, response, and error
signals are developed inside the Chesapeake
unit essentially as described for the Litton unit.
The speed servoamplifier contains logic circuits
which convert the a.c. error signal into d.c.
pulses. The logic circuits are controlled by an
oscillator which determines the rate at which
the pulses are produced. The polarity of the
pulses depends on the polarity of the error
signal. Both the pulses and error signal are
always of such polarity that the servomotor
drives in the direction that will eliminate theiru
Tlie speed servomotor (a d.c. stepping motor)
is stepped by the d c. pulses. Each pulse from
the servoamplifier causes the servomotor to
step 1.8 in response to the pulses. As previously
stated the rate of pulses from the amplifier,
and therefore, the speed at which the servomotor
steps, is dependent on the oscillator. The oscil-
lator can produce two different frequencies.
The higher of the two frequencies triggers the
logic circuits at such a rate that pulses are
produced which cause the servomotor to respond
to speed changes at a rate of 40 knots per minute.
The lower frequency of the oscillator limits
the response of the logic circuits, so that the
rate at which the pulses are produced will
drive the servomotor at a rate of 8 knots per
minute.
The slow speed is used to smooth out oscil-
lations of the rodmeter signal which are caused
by ship's motion (other than forward motion)
or water turbulence. The servomotor drives
the response potentiometer, speed dial, and the
five synchro speed transmitters, as well as
provides a mechanical input for the solid state
distance integrator.
Five different speed signals are produced
by the speed synchro transmitters a 60-hertz
signal at 40 knots/360 and 100 knots/360 and
a 400-hertz signal at 10 knots/360 , 40 knots/360 ,
181
r
*U MVU I 0V Hi.
VjyiSjp
100 KNOT 60 HZ
H3t i
MUST
DIAL
5
40 KNOT 400 HZ (jf^ 1
I SPEED
f SYNCHRO
1
TRANSMITTERS
100 KNOT 400 HZ
<Q| 1
SYNCHRO
1
"""* TRANSMITTER
x jT'>-~S7*^
10 KNOT 400 HZ
nyrfSi i y
HIQTA IMPF" -^ -/ //
7 (l(ur\
vw
SIGNAL TO-
SHIP'S-* \ V
REMOTE CONTROL |
WIRING ^
L^v
UNIT
l^^d
|
-^HA ND C R ANK
A-C r n ~ r //X ^
-x.
\ ^ ^
INPUT
TRANSFORMER
ERROR ^ f
'* A m n ere / sp
RVO 1 SOLID STATE -
PULSES / r-
/- Q r- r- p. . hb^. .j,,,. I SK
^SIGNAL
SPEED ' w ^
SERVO / \MC
TOF J DISTANCE "
V INTEGRATOR /
AMPLIFIER
. _
1 4
A ~ c 4 4
/RESPONSE\ .
POTENTI- '
RESPONSE SIGNAL
OMETER
RODMETER
MILES COUNTER
L
INDICATOR -TRANSMITTER
Figure 9-29. Block diagram of Chesapeake Underwater Log System.
and 100 knots/360 . The 40-knot/360 60-hertz
output drives the ship's speed repeaters* The
other outputs supply speed information to fire
control and navigation equipment.
The solid state distance integrator receives
a mechanical input from the speed servo * This
mechanical input is converted to an electrical
signal which represents the ship's speed. The
electrical speed signal is measured inside the
solid state integrator where pulses are produced
at a rate proportional to the magnitude of the
speed signal. These pulses are applied to the
distance stepmotor, which drives the distance
synchro transmitter and miles counter at a
rate which corresponds to the distance traveled
through water.
When the Chesapeake underwater log system
is operating as a dummy log system, the speed
input signal from the rodmeter is disconnected
from the indicator transmitter. An estimated
ship's speed may be set into the indicator-
transmitter either manually through the use
of the handcrank or through the remote c
unit shown in figures 9-28 and 9-29
indicator-transmitter transmits both the
mated speed and the ship's distance ba
the estimated speed to the ship's speed rej
and equipment.
DUMMY LOG SYSTEM
Before the development of the Ches
underwater log system, a separate dum]
system was installed aboard ships a The i
consists of a speed transmitter and a di
transmitter o The speed transmitter was no
located at the main engineroom control
and was used to set the estimated ship's
into the system . The distance transmitter n
the control signal from the speed trans:
The distance transmitter then transmittec
and distance to the ship' s repeaters andequi
182
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
UNDERWATER LOG
SPEED CONVERTER
The underwater log speed converter, like
the dummy log system, is required on most
ships that do not have a Chesapeake underwater
log system. All underwater log and dummy
log systems prior to the development of the
Chesapeake underwater log system contained
only one speed transmitter synchro. All those
systems transmitted speed as a 40 -knot/360
(1 knot graduation for every 9 on dial face),
60-hertz signal. However, newer equipment was
developed that required speed information other
than 40-knots/360 60-hertz. The speed converter
acts as an interface unit between the newer
equipment and the older underwater/dummy log
systems. The speed converter receives a 40-knot/
360, 60-hertz speed signal and, through the use
of a servo system and gearing, repositions
five synchro transmitters which then transmit
10-knot/360, 40-knot/360, 100-knot/360 400-
hertz; 10-knot/360, 100-knot/36060-hertz speed
signals to equipment that requires them. Figure
9-30 illustrates the speed converter in the
underwater /dummy log system and shows the
difference between typical Litton and Chesapeake
systems.
DEAD RECKONING
SYSTEMS
The dead reckoning systems provide a means
of plotting the ship's position graphically on an
REMOTE CONTROL UNIT
CHESAPEAKE
UNDERWATER
LOG
SYSTEM
60 HERTZ DISTANCE
60 HERTZ 40 K/360 SPEED
60 HERTZ 100 K/360 SPEED
400 HERTZ 10 K/360 SPEED f"
400 HERTZ 40 K/360 SPEED
TO SHIP'S EQUIPMENT
AND
REPEATERS
400 HERTZ 100 K/360 SPEED J
60 HERTZ
SPEED AND
DISTANCE
I.C
AGO -
SWITCH
60 HERTZ
60 HERTZ 10 K/360 SPEED |
60 HERTZ 100 K/360 SPEED
400 HERTZ 10 K/360 SPEED > TO EQUIPMENT
400 HERTZ 40 K/360 SPEED
4OO HERTZ 100 K/360 SPEED J
SPEED AND
DISTANCE
B
60 HERTZ DISTANCE AND
40 KNOT/360 6O HERTZ
SPEED TO REPEATERS
AND EQUIPMENT
27.386
Figure 9-30. Underwater and Dummy Log Installations: (A) Chesapeake, (B) Litton, including dummy
log and speed converter.
183
SHIPBOARD ELECTRICAL SYSTEMS
appropriate chart, plotting the ship's track, and
plotting targets relative to the ship's position.
Most dead reckoning systems also indicate the
ship* s position in latitude and longitude on mechan-
ical dials.
There are several different types of dead
reckoning equipment. In this section we shall
discuss the Arma system, various NC-2 plotting
systems, and the Mk 6 Mod 4B Dead Reckoning
Tracer used in conjunction with the Mk 9
Mod 4 Dead Reckoning Indicator Analyzer.
ARMA DEAD RECKONING
EQUIPMENT
The Arma dead reckoning equipment (DRE)
contains (1) a dead reckoning analyzer and
(2) a dead reckoning tracer. A block diagram of
the dead reckoning system is illustrated in
figure 9-31.
input from the ship's gyrocompass. The DRA
using the ship's course input, resolves th
ship's distance input into rotary E-W and N-
distance components. This information is dis
played on counters located inside the DRA an
is transmitted by the d.c. step transmitters I
the Arma dead reckoning tracer.
Arma Dead Reckoning
Tracer
The dead reckoning tracer (DRT) (fig. 9-3;
consists of (1) a tracking mechanism, (2)
chart board that includes the pencil carriai
assembly, and (3) an auxiliary plotting boar
The auxiliary plotting board, which is the gla
top of the DRT, is used for plotting ranges a
bearings of contacts that are being tracked a
for plotting own ship's position. The DRT
housed in a metal case designed for horizonl
mounting on a table or cabinet and is usua
located in the combat information center.
Arma Dead Reckoning
Analyzer
The dead reckoning analyzer (DRA) (fig.
9-32) receives the ship's distance input from
either the underwater or dummy log system. This
input is in the form of a rotary motion, the rate
of rotation being directly proportional to ship's
speed. The DRA also receives the ship's course
The tracking mechanism of the DRT contai
the step-by-step receivers and gears that positi
the pencil carrier assembly in response to 1
E-W and N-S distance inputs from the DRA. The
are two such receivers and gear trains 1
cross screw drive assembly and the lead scr
drive assembly. The cross screw and le
screw drive assemblies position the pencil carr
assembly along the axes shown in figure 9-
OWN
SHIPS COURSE
N.S.
DISTANCE
.- .. -. - Jlllini
MASTER
GYRO-
COMPASS
DEAD
RECKONING
TRACER
hit
DEAD
RECKONING
ANALYZER
E.W.
DISTANCE
OWN
SHIP'S
DISTANCE
I, C. ACO
SWITCH
40.
Figure 9-31. Dead reckoning system, block diagram.
184
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
EAST MILES COUNTER TOTAL MILES COURSE SYNCHRO AND SHIP'S DISTANCE
COUNTER \ FOLLOW-UP HEAD /SYNCHRO RECEIVER
EAST STEP
TRANSMITTER
NORTH MILES
COUNTER
NORTH STEP
TRANSMITTER
COURSE
FOLLOW-UP
MOTOR
40.57
Figure 9-32 Arma dead reckoning analyzer
By means of a switch either axis maybe selected
to represent a N-S direction. That is, either
the lead screw or cross screw drive assemblies
in ay be actuated by the N-S or E-W distance
input. Both drive assembly gear trains are
adjustable and may be shifted to provide four
different tracking scales so that 1 inch of move-
ment by the pencil carriage assembly may
represent from 200 yards to 16 miles of ship's
movement.
The chart board consists of a recessed
plotting surface in the left-hand section of the
DRT case below the pencil carriage assembly
(fig. 9-33). A pencil, attached to the pencil
carriage assembly, automatically traces the
movements of the ship on a chart inserted on
the plotting surface.
The pencil carrier assembly is illustrated
in figure 9-34. The pencil carrier assembly
is supported by the pencil carriage assembly
and includes the pencil, the pencil magnet, and
the range-bearing projector. The pencil magnet
is actuated by a clock-driven switch located
with the tracer mechanism which energizes
185
SHIPBOABD ELECTRICAL SYSTEMS
CLOCK- SWITCH
TRACER MECHANISM
RANGE- BEARING
PROJECTOR ASSEMBLY
LEAD SCREW
DRIVE
ASSEMBLY
PENCIL CARRIAGE
ASSEMBLY
CHART
BOARD
CROSS
SCREW
DRIVE
AXIS
DEAD
RECKON I MS-
INDICATOR
LEAD SCREW
DRIVE AXIS
CROSS SCREW
DRIVE
ASSEMBLY
CROSS SCREW
HAMDWHEEL
Figure 9-33. Arma dead reckoning tracer and dead reckoning indicator.
40.61(40
the pencil-magnet circuit at predetermined inter-
vals. This action causes the magnet to lift the
pencil from the chart periodically to omit the
trace to facilitate interpreting the plot. The
range-bearing projector assembly (plotting light)
is mounted on the pencil carrier for use in
conjunction with the auxiliary plotting board
to indicate the own ship's position at all times*
It projects a polar diagram display on the
underside of the auxiliary plotting board. This
projected polar diagram is used to plot own
ship's track, position, and the position of targets
relative to the ship*
Dead Reckoning Indicator
The dead reckoning indicator (DRI) (fig. 9-3;
is located with the tracking mechanism of t
dead reckoning tracer. It consists of a dial ui
assembly that includes the latitude motor (driv
by N-S distance signal from DRA), the longitu
motor (driven by E-W distance signal from DR^
and dialSo The latitude and longitude dial asset
blies each consist of two concentric dials. T
outer latitude and longitude dials are graduat
in degrees, and the inner latitude and longitu
dials are graduated in minutes.
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
RANGE -BEARING
PROJECTOR
QUICK-RELEASE
OPERATING LEVER
PENCIL-
PENCIL CARRIER
SUPPORTS
40.62
Figure 9- 34 - Pencil carrier and range-bearing
projector assembly.
NEW DESIGN DEAD
RECKONING EQUIPMENT
One of the Navy's newer dead reckoning equip-
ment systems consist of the Dead Reckoning
Analyzer Indicator (DRAI) such as the Mk 9
Mod 4 (DRAI) and the Mk 6 Mod4B Dead Reckon-
ing Tracer (DRT). Figure 9-35 is a block diagram
of this equipment.
Mk 9 Mod 4 DRAI
The Mk 9 Mod 4 DRAI (fig. 9-36) is a hybrid
analog/digital device which continuously com-
putes, transmits, and displays principal naviga-
tion inform ation. The DRAI accepts synchro
information of own ship's speed from the ship's
underwater log system and own ship's heading
from the ship's gyrocompass sy stein .Information
required for dead reckoning is calculated from
these signals and displayed on the various dials
and counters on the front of the DRAI. Some
of the information is electrically transmitted
to related shipboard equipment. Figure 9-35
illustrates which information is displayed and
transmitted by the Mk 9 Mod 4 DRAI.
The DRAI is used aboard surface ships and
submarines. It can drive up to four Mk 6 Mod 4B
DRT's simultaneously. When properly maintained,
the DRAI is much more accurate than the Arm a
DRA.
INPUTS
FINE
/COARSE
lit
en
de
*
n-
DRAI
MK-9 MOD 4
COARSE ^
LATITUDE
^LONGITUDE
VELOCITY N-S
"VELOCITY E-W
DISTANCE N-S ^
MK-6 MOD 4B
ORT
FINE
COARSE ^
FINE ^
DISPLAYED OUTPUTS
DISPLAYED OUTPUTS
OWN SHIPS SPEED
OWN SHIPS HEADING
VELOCITY N-S
VELOCITY E-W
TOTAL OWN SHIPS
DISTANCE TRAVELED
DISTANCE
TRAVELED N-S
DISTANCE
TRAVELED E-W
LATITUDE
LONGITUDE
COARSE ^
LATITUDE
LONGITUDE
SHIP POSITION
FINE >
COARSE ^ ""
FINE m
DISTANCE E-W
Figure 9-35. Block diagram of the Mk 9 Mod 4 DRAI and Mk 6 Mod 4B
187
40.56 (40D)
SHIPBOARD ELECTRICAL SYSTEMS
Figure 9-36. DRAI Mk 9 Mod 4 dead reckoning analyzer indicator.
40.147(4
Dead Reckoning Tracer
Mk 6 Mod 4B
The Mk 6 Mod 4B Dead Reckoning Tracer
(DRT) (fig. 9-37) graphically records own ship's
dead reckoning track and computes and displays
own ship's latitude and longitude on counter s a
The DRT operates automatically from input
signals of distance north and distance east from
the step transmitters in the DUAL The east
and north distance inputs from the DRAI drives
the lead and cross screw mechanisms which
position the pencil carriage/projector assembly
and record the ship's track. Latitude and longi-
tude are also continuously computed from the
two distance inputs and are displayed on counters.
The Mk 6 Mod 4B DRT mechanisms are similar
to, but more modern than, those of the Arm a
DRT.
NC-2 PLOTTING
SYSTEMS
The NC-2 plotting system was develo]
primarily to aid Combat Information Cer
watch personnel in plotting ship's position
the position of contacts relative to own si
The original system has been improved
modified,, There are now several different N<
plotting systems in use throughout the Ns
Each of the systems usually consists of a I
or a DRAI f and a plotting table. The ploti
table serves the same purpose as the Ai
DRT, plus being capable of displaying the loca'
of from two to four targets relative to
position of the ship.
NC-2 Mod
The NC-2 Mod (MARSLAND) was the origi
plotting system. The system consists of th
188
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
Figure 9-37. Dead reckoning tracer Mark 6 Mod 4B
40.6(40D)A
major units the plotting table, a dead reckoning
indicator, and a data converter (fig. 9-38).
The plotting table houses three projectors,
which are used for plotting the positions of own
ship and two targets. The main projector assembly
projects a polar diagram on the undersurface
of the translucent table top. This polar diagram,
the center of which represents own ship, moves
in response to own ship's movements. Two
smaller projectors, called target plot attach-
ments (TPA's) project colored spots of light on
the underside of the table top to represent the
locations of the targets in relation to own ship*
Each of the two TPA's projects a different
colored spot of light one green, the other red
so that the movement of the two targets may be
followed with minimum confusion. Through the
use of selector switches, either TPA may be
controlled by range and bearing information from
radar, sonar, fire control equipment, or other
sources.
The dead reckoning indicator provides a
reading on a counter of the geographical position
of the ship's latitude and longitude. Use of the
dead reckoning indicator is optional. The re-
mainder of the plotting system is independent
of the dead reckoning indicator and may be
used without it
The data converter receives range and speed
data from the ship's radar, sonar, fire control
equipment, and underwater log equipment, and
converts this data into a form usable by the
plotting table*
NC-2 Mod 1/1A
The NC-2 Mod 1 (Sperry) consists of two
major units: a bulkhead-mounted dead reckoning
189
SHIPBOARD ELECTRICAL SYSTEMS
DEAD RECKONING INDICATOR
MAIN CONTROL PANEL A6
Figure 9-38. Plotting system Mk NC-2
74,
indicator (DRI) and a plotting table. The DRI ship's position and the position of as many
employed in this system is an electromechanical four separate targets* As in the previous syste
computer which computes latitude, longitude, own ship is represented by the center of 1
and N-S and E-W speed from ship's gyro and polar diagram, and each target is represenl
underwater log inputs The plotting table is by a different colored spot of Iight Each
capable of providing a pictorial display of own the four TPA's may be controlled by inputs fr<
190
Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS
ship's radar, sonar or fire control equipment
through a selector switch arrangement.
The NO 2 Mod 1A (Sperry) system is a
ruggedized version of the NC-2 Mod 1 system.
NO 2 Mod 2/2A
The NC-2 Mod 2/2A systems (Hartman) con-
sist of two units each: (1) a dead reckoning
analyzer indicator (DRAI) or a dead reckoning
indicator (DRI), which computes own ship's dead
reckoning position and (2) a plotting table, which
displays own ship's position and the positions
of four separate targets.
The NC-2 Mod 2 and Mod 2A have identical
plotting tables. The systems differ in that the
Mod 2 is supplied with a Mk 8 DRI and the Mod
2A is supplied with a Mk 9 Mod or Mk 9 Mod 2
DRAI. Since the Mod 2A is the most common
system used, we shall discuss its operation,
MK 9 DEAD RECKONING ANALYZER
INDICATOR. The Mk 9 Mod DRAI (fig, 9-39)
is designed for direct bulkhead mounting and
27,387
Figure 9-39. ASW plotting system NC-2 Mod 2-A: (A) NC-2 Mod 2 Plotting Table, (B) Mk 9 Mod DRAI.
191
SHIPBOARD ELECTRICAL SYSTEMS
can be operated as an independent unit or in
conjunction with, and as a part of, the NC-2
Mod 2A plotting system. When used with the
NC-2 Mod 2A plotting system, the DRAI is
electrically connected to the NC-2 Mod 2 plotting
table ,
There are two versions of the DRAI used with
the NC-2 Mod 2 plotter: the Mk 9 Mod DRAI,
designated the standard unit; and the Mk 9 Mod 2
DRAI, designated the low noise or "silent"
unit. Only minor differences exist between the
two versions.
The DRAI is an electromechanical computer,
employing digital circuits that receive inputs
of own ship's speed (OSS) and own ship's course
(OSC). From these inputs, the N-S and E-W
components of ship's speed are computed for
internal use within the DRAI and for trans-
mission to external shipboard equipment. In
addition, OSS is integrated with respect to time
to give a counter readout of total distance
traveledo
The N-S and E-W speed components are
also integrated to provide a counter readout
of distance traveled in the N-S or E-W direction.
The DRAI supplies a counter readout of ship's
latitude and longitude, computed from the N-S
and E-W components of ship's speed. The DRAI
can transmit computed values of latitude, longi-
tude, present ship's position in N-S and E-W
components, own ship's speed N-S and E-W
and change of position in N-S and E-W components.
The Mk 9 DRAI is also capable of trans-
mitting N-S and E-W distance information in a
d.c. step form that may be used to drive the
previously described Mk 6 Mod 4B DRT.
PLOTTING TABLE NC-2 MOD 2. The NC-2
Mod 2 plotting table, although more modern
in design, essentially performs the same functions
as the other plotting tables,, The plotting table
is capable of graphically displaying own ship's
position and four air, surface, or underwater
targets on the plotting surface.
PT-512/S Tactical Display
Plotting Table (formerly
NC-2 Mod 3)
Unlike the other NC-2 systems, the PT-512/S
tactical display plotting table consists of only
one unit which is an upgraded version of the
NC-2 Mod 2 plotting table. The components of
the DRAI that were necessary to operate the
plotting table have been relocated inside the
plotting table, thus eliminating the necessity
of the DRAI. The PT-512/S plotting table operates
as the previously described plotting tables. It
receives synchro speed and course data from the
underwater log and gyrocompass and converts
the data to analog signals which position the
polar diagram. The four TPA's receive their
inputs through a selector switch that enables
the operator to select any of nine target range
and bearing inputs.
The PT-512/S tactical display plotting table
provides a numerical readout of ship's speed
and heading. The system doe snot provide displays
of latitude or longitude, as do the other systems,
The PT-512/S plotter produces d,c, step outputs
that may be used to drive the Mk 6 Mod 4B DRT,
192
CHAPTER 10
INTERIOR COMMUNICATIONS
TELEPHONE SYSTEMS
Telephones provide a rapid and efficient
means of communication between the many sta-
tions aboard ship. A satisfactory telephone system
must be reliable; must not be susceptible to
damage during battle; must be able to make
rapid completion of calls; and must be easy
to maintain. The sound-powered telephone fulfills
these requirements. As the name implies, the
sound-powered telephone requires no outside
power supply for its operation. The sound waves
produced by the speaker's voice provide the
necessary energy to reproduce the voice at a
remote location.
In addition to sound-powered telephones, dial
telephones are provided aboard some ships.
The dial telephone system is used for adminis-
trative purposes and is not depended on under
battle conditions.
SOUND-POWERED
TELEPHONES
The sound-powered transmitter (microphone)
and receiver units in some sound-powered tele-
phones are identical and interchangeable. Other
telephones have sound-powered units that differ
slightly The principle of operation, however, is
the same for both the transmitter and receiver.
As illustrated in figure 10-1 a unit consists
of two permanent magnets, two pole pieces,
an armature, a driving rod, a diaphragm, and a
coil. The armature is located between four
pole tips, one pair at each end of the armature.
The spacing between the pole tips at each end
is such that an air space remains after the
armature is inserted between them. This air
space has an intense magnetic field, which is
supplied by the two magnets that are held in
contact with the pole tips.
The armature is clamped rigidly at one
end near one of the pairs of poles and is con-
nected at the other end to the diaphragm by the
drive rod. Hence, any movement of the diaphragm
causes the free end of the armature to move
toward one of the pole pieces. The armature
passes through the exact center of a coil of
wire that is placed between the pole pieces
in the magnetic field.
The armature of a transmitter unit, when
there are no sound waves striking the diaphragm,
is shown in figure 10-1A Sound waves striking
the diaphragm cause it to vibrate back and forth
(fig. 10-1B and C). The armature bends first to
one side and then to the other, causing an
alternating polarizing flux to pass through it,
first in one direction and then in the other.
These lines of force passing through the arma-
ture vary in strength and direction, depending
on the vibrations of the diaphragm. This action
induces an emf of varying direction and mag-
nitude- that is, an alternating voltage in the
coil. The alternating voltage has a frequency
and waveform similar to the frequency and
waveform of the sound wave striking the dia-
phragm.
When the coil of a transmitter unit (fig.
10- 2A) is connected to the coil of a receiver
unit (fig. 10-2B), the diaphragm of the receiver
unit will vibrate in unison with the diaphragm of
the transmitter unit and thus generate corre-
sponding sound waves.
The two types of sound-powered telephones
installed aboard Navy ships are handsets and
headsets. All telephones of a given type are
built to the same military specifications regard"
less of the manufacturer.
HANDSETS
The type H-203/U handset is designed for
general use, primarily one-to-one talking. Tlie
sound-powered transmitter and receiver units
are interchangeable. SI, a nonlocking, normally
open, spring-return push switch, (fig. 10-3)
disconnects the sound-powered units from the
line in the open position and connects the units
to the line in the closed (depressed) position.
Capacitor Cl is connected in parallel with the
sound-powered units for tone compensation.
193
SHIPBOARD ELECTRICAL SYSTEMS
MAGNET
COIL
ARMATURE
B
Figure 10-1.- Sound-powered transmitter receiver unit.
27.28
HEADSETS
TRANSMITTER
A
RECEIVER
B
Figure 10-2. Operation of sound-powered units.
27.28!
The type H-200/U headset is designed for
general use as well as for use with transistor-
ized sound-powered telephone amplifiers.
When a sound-powered telephone set is used
on the output side of a sound-powered telephone
amplifier, a small d.c. voltage is placed across
the set to provide an amplifier squelching circuit
to avoid acoustical feedback when the local se
is transmitting. Capacitor Cl (fig. 10-4) prevent
the flow of d.c. through the receiver units
When the press-to-talk switch is depressed
d.c. current flows through the transmitter uni
causing a relay in the amplifier to operat
and activate the squelching circuit. Capacito
C2 provides power-factor correction and im
proves the acoustical quality of the sound
powered headset. The sound-powered transmitte
194
TWISTED PAIR
LINE CORD
SOUND-POWERED
RECEIVER UNIT
SOUND-POWERED
''"TRANSMITTER
UNIT
Figure 10-3. Wiring diagram of a sound-powered telephone handset.
and receiver units of headsets are not inter- SOUND-POWERED
TELEPHONE SYSTEMS
CIRCUITg
3.198
The type H-202/U headset is a specially
designed set for use in areas that have high As classified by usage there are three types
noisi levels. The receiver units are housed in of sound-powered telephone circuits:
noise attenuating shells plastic caps lined with
sound absorbing material. The sound-powered 1. The primary battle telephone circuits JA
units are not interchangeable, to JZ (table 10-1) include all circuits used for
RECEIVER
RECEIVER
140.33
Figure 10-4. Wiring diagram of a sound-powered telephone headset.
195
SHIPBOARD ELECTRICAL SYSTEMS
Table 10-1. Sound- Powered Telephone Circuits
Circuit
Primary Circuits
Title
JA
JC
10JC
JD
JF
1JG
2JG
2JG1
2JG2
2JG3
3JG
4JG1
4JG2
4JG3
5JG1
5JG2
6JG
9JG
10JG
11JG
JH
JL
JK
JM
JN
JO
2JP
4JP
5JP
6JP
8JP
9JP
10JP
Captain's battle circuit
Weapons control circuit
Missile battery control circuit
Target detectors circuit
Flag officer's circuit
Aircraft control circuit
Aircraft information circuit
Aircraft strike coordination circuit
Aircraft strike requirement and reporting circuit
Aircraft information circuit CATTC direct line
Aircraft service circuit
Aviation fuel and vehicular control circuit
Aviation fueling circuit forward
Aviation fueling circuit aft
Aviation ordnance circuit
Aviation missile circuit
Arresting gear and barricade control circuit
Aircraft handling circuit
Airborne aircraft information circuit
Optical landing system control circuit
Switchboard cross connecting circuit
Lookouts circuit
Double purpose fuse circuit
Mine control circuit
Illumination control circuit
Switchboard operators' circuit
Dual purpose battery control circuit
Heavy machine gun control circuit
Light machine gun control circuit
Torpedo control circuit
ASW weapon control circuit
Rocket battery control circuit
Guided missile launcher control circuit
27.337
196
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
Table 10-1. Sound- Powered Telephone Circuits Continued
Circuit
Primary Circuits
Title
10JP1
10JP2
11JP
JQ
JR
JS
US
2JS
3JS
20JS1
20JS2
20JS3
20JS4
21JS
22JS
23JS
24JS
25JS
26JS
31JS
32JS
33JS
34JS
35JS
36JS
61JS
80JS
81JS
82JS
JT
1JV
2JV
Starboard launcher circuit
Port launcher circuit
FBM checkout and control circuit
Double purpose sight setters circuit
Debarkation control circuit
Plotters' transfer switchboard circuit
CIC information circuit
NTDS coordinating circuit No. 1
NTDS coordinating circuit No-. 2
Evaluated radar infortxiation circuit
Evaluator's circuit
Radar control officer's circuit
Weapons liaison officer's circuit
Surface search radar circuit
Long range air search radar circuit
Medium range air search radar circuit
Range height finder radar circuit
AEW radar circuit
Radar information circuit
Track analyzer No. 1 air radar information check
Track analyzer No. 2 air radar information check
Track analyzer No. 3 air radar information check
Track analyzer No. 4 air radar information check
Raid air radar information circuit
Combat air patrol air radar information circuit
Sonar information circuit
ECM plotters' circuit
ECM information circuit
Supplementary radio circuit
Target designation control circuit
Maneuvering and docking circuit
Engineers' circuit (engines)
27.3
197
SHIPBOARD ELECTRICAL SYSTEMS
Table 10-1. Sound-Powered Telephone Circuits Continued
Circuit
Primary Circuits
Title
3JV
4JV
5JV
6JV
11JV
JW
JX
2JZ
3JZ
4JZ
5JZ
6JZ
7JZ
8JZ
9JZ
10JZ
11JZ
Engineer's circuit (boiler)
Engineer's circuit (fuel and stability)
Engineer's circuit (electrical)
Ballast control circuit
Waste control circuit
Ship control oearing circuit
Radio and signals circuit
Damage and stability control
Main deck repair circuit
Forward repair circuit
After repair circuit
Midships repair circuit
Engineer's repair circuit
Flight deck repair circuit
Magazine sprinkling and ordnance repair circuit forward
Magazine sprinkling and ordnance repair circuit aft
Gallery deck and island repair circuit
Auxiliary Circuits
XJA
X1JG
X1JV
XJX
X2JZ
Auxiliary captain's battle circuit
Auxiliary aircraft control circuit
Auxiliary maneuvering and docking circuit
Auxiliary radio and signals circuit
Auxiliary damage and stability control circuit
Supplementary Circuits
X1J
X2J
X3J
X4J
X5J
X6J1
X6J7
X6J11-14
X7J
Ship administration circuit
Leadsman and anchor control circuit
Engineer watch officer's circuit
Degaussing control circuit
Machinery room control circuit
Electronic service circuit
ECM service circuit
NTDS service circuits
Radio-sonde information circuit
27.331
198
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
Table 10-1. Sound-Powered Telephone Circuits Continued
Circuit
Supplementary Circuits
Title
X8J
X9J
X10J
X10J1
X10J10
XI 1J
X12J
X13J
X14J
XI 5 J
XI 6 J
XI 7 J
XI 8 J
XI 9 J
X20J
X21J
X22J
X23J
X24J
X25J
X26J
X28J
X29J
X34J
X40J
X41J
X42J
X43J
X44J
X45J
X50J
X61J
Replenishment-at-sea circuit
Radar trainer circuit
Cargo transfer control circuit
Cargo transfer circuit-Lower decks
Cargo transfer circuit-Upper decks
Captain's and admiral's cruising circuit
Capstan control circuits
Aircraft crane control circuits
Missile handling and nuclear trunk crane circuit
SINS information circuit
Aircraft elevator circuit
5-inch ammunition hoist circuit
Machine gun ammunition hoist circuits
Missile component elevator circuit
Weapons elevator circuits
Catapult circuit
Catapult steam control circuit
Stores conveyor circuit
Cargo elevator circuit
Sonar service circuit
Jet engine test circuit
Dumbwaiter circuit
Timing and recording circuit
Alignment cart service circuit
Casualty communication circuit
Special weapons shop service circuit
Missile assembly and handling circuit
Weapons system service circuit
ASROC service circuit
Special weapons security circuit
Fog foam circuit
Nuclear support facilities operations and handling circuit
27.337
from the wiring of the corresponding primary
circuits to lessen the possibility of battle damage
to both circuits.
3. The supplementary telephone circuits X1J
through X61J consist of circuits that provide
communications for various administrative,
service, and secondary control functions.
The various sound-powered telephone systems
are classified by construction into three groups;
switchboard circuits, switchbox circuits, and
string-type circuits.
Switchboard Circuits
A switchboard circuit (fig. 10-6) has the lino
for each telephone station connected to an indi-
vidual ewitchjaok. The ewitchjack (fig. 10-5A)
le a combination line cutout switch and telephone
jack. Each switohjack is mounted in rows on the
switchboard (fig. 10-GB). The lino cutout switch
portion of the swltchjack either connects or
disconnects a telephone station from Its circuit.
The Jack portion of the switohjack is usotl with
a patching cord to either parallel tho telephone
station associated with a particular Bwltchjack
to another circuit or servos to pnrallul two
entire circuits.
Most largo combatant ships have eovoral
sound-powered telephone switchboards installed
in different centrally located and protected control
stations. Bach switchboard usually has facilities
to control several switchboard circuits.
Switchbox Circuits
A switchbox circuit has the line for oach
telephone station connected to one of the Indi-
vidual cutout switches which are mounted in a
switchbox (fig. 10-6). Each cutout switch either
connects or disconnects an individual telephone Figure lQ-5.
station to a circuit.
200
2'
Sound-power od telephone B
and switchjack.
27. 29 IX
,ound~poworod telephone Bwilohbox.
10 Bwltohoa nmy bo used as tlo
:jctod to Uio circuit bus in other
'hon Ihuuu llo HwlLuhuH tiro closed,
i tho two l)oxoB arc paralleled,
oro 1ft only ono nwllahbox for caoh
,ono swltchboxoR function primarily
) switchboards Tho awituhboxos
Lho principal Htallon on tho circuit,
hor 10 or 20 swllchua.
IroullB
pu circuit uoiislftlB of a eorloa
station JriokboxoH connected In
single Him. Thoro are no action
for Individual HtaUona.
casually communication clroull,
Hot) H Htrln^-typu ulroulU con-
dual rlKor unbluH ruuuliiK from
jnglnuurinf"; HpauuB and Bluurlng
four tffing JftckboxoH on Uio main
u 10-7.
ital runw aru ni.-ido an roqulrod
irol partloH with rolls of oabloa,
,o up on ruulB with i>lugB on onoh
for
ansfor switchboards (fig. 10-8)
IGS arranged in a matrix form,
jnt Bound-poworod jaokboxos and
:onnootod to thoso ewllchboat'ds.
140.187
Figure 10-7, X40J circuit risers.
As shown in figure 10-8B, the closing of any
one of the five switches associated with each
jaokbox permits the Jackbox to be connected
to one of the sound-powered circuits. In figure
10-8J3 jaokbox JS1 is shown connected to sound-
poworod circuit 22JS, and jaokbox JS2 is shown
connected to sound-powered circuit 81JS. Any
of the remaining jaokboxes, JS3-JS10 may be
connected to ono of the five sound-powered
circuits by simply closing the associated switch,
Plotters transfer switchboards are found in
aroae aboard ship such as C1C ( whore the
tactical situation governs the sound-powered
circuit to which the plotters are to be connected.
For Instance, the situation may require that the
CIC plotters connected to jackboxos JS1- JS6 be
'connected to circuit 21JS, while tho plotters
connected to juckboxee JS6 - JS10 are connected
to circuit 22JS. Another situation may call for
another arrangement. The plotters transfer
switchboard permits the plotters to be shifted
from ono circuit to another quickly and effi-
ciently ns tho situation dictates and eliminates
tho necessity of Installing multiple circuit phone
boxas at oaoii location.
Selector Switches
Selector switches (fig, 10-9) are located
at tho most Important stations throughout the
ship to enable the officer in charge, or his
talker, to connect his telephone to any one of
a group of circuits without having to change
from ona Jaokbox outlet to another.
SHIPBOARD ELECTRICAL SYSTEMS
CIC SECT.
JS-I
LEGEND:
H- INDICATES OPEN SWITCH
-f INDICATES CLOSED SWITCH
(A)
INPU1
CVJ 10 "3-
CVJ <NJ <VI CNJ OO
JACKBOX
o
T
- A
I
^
S.P.
JACKBOX
1
O
JS-2
S.P.
> JACKBOXES
JS3-JS10
CIRCUIT 81JS
CIRCUIT 24JS
CIRCUIT 23JS
CIRCUIT 22JS
riprniT 91 .ic
SP
SP
SP
SP
SP
rc-fe
#:::S
^5::?::::
Mi^
iil^:
j)
(B)
Figure 1 0- 8 Plotters transfer switchboard.
36.69
SOUND- POWERED
TELEPHONE
CIRCUIT MAINTENANCE
SOUND- POWERED
TELEPHONE AMPLIFIER
AM-2210/WTC
Preventive maintenance for sound-powered
telephone circuits consists of routine tests,
inspections, and cleaning, which should be con-
ducted in accordance with current PMS require-
ments. Cleanliness is essential to the proper
operation of sound-powered telephone equipment
because of the low voltages and currents involved.
In high noise-level areas such as engineering
control, steering engine rooms, and gun mounts,
it is often difficult, if not impossible, to hear
sound-powered telephone conversations, even
over the best maintained circuits. Recognizing
this, the Navy developed the sound-powered
telephone amplifier to assist communications
202
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
27.388
Figure 10-9. Selector switch.
in these vital areas. The transistorized AM-
2210/WTC, presently in wide use throughout
the fleet, meets the following requirements with
a high degree of reliability:
1. Amplifies one-way communications in a
two-way sound-powered system using existing
sound-powered headsets. (That is, it amplifies
the voice to a gun mount but not the voice from
it.)
2. Supplies six outlet headsets and two loud-
speakers.
3. Is fail-safe on power loss or component
failure. (Allows normal level conversation.)
4. Operates on 115-volt 60-hertz a.c. power.
When operating under normal conditions, the
AM-2210/WTC (fig. 10-10) receives signals from
a remote telephone line, amplifies them, and
transmits the amplified signal to as many aa
six local headsets and two loudspeakers. Direct
talk-back between any of the six headsets and
the remote line is carried out at normal sound-
powered level, the amplifier being disconnected
140.71
Figure 10-10.- Sound-powered telephone amplifier
AM-2210/WTC.
upon actuation of any of the press- to- talk switches
on any of the six local headsets.
When the amplifier is deenergized or when
certain predetermined casualties occur, the fail-
safe feature permits direct two-way communi-
cations between local and remote stations at
a normal sound-powered level.
Electrically the unit consists of an audio
amplifier, a switching circuit, and a power
supply. Equipment reliability is increased by
the use of transistors in the audio and switching
circuits.
Although by no means trouble free, the AM-
2210/WTC is a reliable unit. When trouble does
occur, it often is caused by improper operating
procedures or by a failure in external circuitry.
CALL-BELL SYSTEMS
Call-bell systems provide a means of signaling
between stations in a ship. These systems consist
of circuits E and A
CIRCUIT E
Circuit E provides a means of signaling
between stations on sound-powered telephone
circuits and outlets on voice tubes. Aboard
203
SHIPBOARD ELECTRICAL SYSTEMS
large ships this circuit may be designated as
follows:
EM Self-contained circuits with m agneto
call signal stations: Provides for selective calls
over COMMON talk circuits.
MJ Self-contained circuits with magneto call
signal stations: Provides for selective calls over
SELECTED talk circuits,
EP Protected call circuits with cable runs
protected behind armor.
EPS Unprotected signal lines supplied from
an EP circuit through separate protected fuses
at the calling station.
EPL- Unprotected circuits supplied from an
EP circuit through a protected local cut-out
switch at the station called.
EX Exposed call circuits with cable runs
not protected behind armor.
In addition, circuit E has the following func-
tional designations:
IE Cruising and miscellaneous
2E Ship control
3E Engineering
4E Aircraft control
5E Fire control
HE through 15E Turrets I through V
For example, a circuit designated as 3EP
is an engineering call-bell circuit with cables
protected behind armor.
Circuits EP and EX require an outside source
of power and include bells, buzzers, or horns
installed at selected sound-powered telephone
stations and at some voice tubes* Watertight
and nonwatertight pushbuttons, or spring return
rotary switches, are provided at all signaling
stations to complete circuits to the station
called. Circuits EM and MJ are self-contained
magneto-powered cell systems which utilize 1C /D
call signal stations, normally called growlers
or howlers (fig. 10-11). They are used in con-
junction with sound-powered telephone systems.
The call signal stations consist of a rotary
selector switch, a hand-operated magneto gener-
ator, and a howler unit. Selective calling of up
to 16 individual stations is possible. When used
in the circuit EM configuration, the sound-
powered telephone and call systems are in-
dependent of each other. In the MJ configuration
the sound-powered telephone and call systems
are combined. Through the use of a relay within
the IC/D Call Signal Station, the sound-powered
conversation is transmittedfrom station to station
via the signaling leads. In the EM configuration
only one conversation is possible at one time.
With the MJ configuration up to 15 separate
conversations are possible at one time.
CIRCUIT A
Circuit A is for the convenience of the ship's
officers in callingpantry attendants and orderlies.
Calls are provided from cabins, staterooms, and
wardrooms to the respective pantries and order-
lies. Circuit A calls are provided also from all
sickbay berths and isolation wards to the attend-
ant's desk in the sick bay. Circuit A consists
of bells or buzzers at the orderly and pantry
stations and nonwatertight pushbuttons in the
various cabins, staterooms, and messrooms.
Where a station is to be signaled by more than
one pushbutton, a drop-type annunciator is in-
stalled in addition to the bell or buzzer.
A simplified call-bell circuit is shown in
figure 10-12. This simplified circuit applies
to circuit A as well as to circuit E.
The upper branch circuit, with one bell and one
pushbutton in series with each other, is used to
call single station from one location.
The center branch circuit, with two push-
buttons in parallel with each other and in series
with the bell, is used to operate one bell from
two remote locations.
The lower branch circuit, with two bells
in parallel with each other and in series with one
pushbutton, is used to operate two bells from
one location.
ANNUNCIATORS
Stations (such as the bridge) that are served
by several sound-powered circuits with their
associated call-bell systems require some aid
to distinguish between the sounds of the various
204
Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
Figure 10-ll e IC/D call signal station.
74.66X
ignals. The need for this aid is especially
ecessary when several magneto call stations
re used because of the similarity of the sound
ley emit. In addition, some means is needed
r ith A call systems to aid in determining which
tateroon) is signaling. Annunciators are used
1th A and E call-bell systems to fulfill these
eeds.
Annunciators used with E call circuits are
f the drop type. The drop, or target, is em-
ossed with the designation of the sound-powered
ircuit with which it is associated and is
eld mechanically in the non-indicating posi-
lon. When the circuit is energized (by
pushbutton or by a turn of the crank of
magneto call signal station at the calling
tation), an electro-magnet causes the target
D drop to the indicating position. The drops
re returned to their normal, or nonindicating
ositions by a hand-operated reset button.
Annunciators used with A call circuits are
similar to those used with E call circuits except,
that in A call circuits, the drop is embossed
with the number of the stateroom, or location
of the calling station, instead of the circuit
letter.
An additional feature of annunciators is the
ability to use a common audible signaling device
controlled by relays in the annunciator.
DIAL TELEPHONE
SYSTEMS
In addition to sound-powered telephone sys-
tems, dial telephone systems are installed on
the Navy's combatant ships. The dial telephone
system, or circuit J, is primarily an adminis-
trative circuit which provides complete selective
SHIPBOARD ELECTRICAL SYSTEMS
telephone communication throughout the ship
The system is also used to supplement other
communication facilities for ship control, fire
control, and damage control. The capacity of
the system varies with the size and needs of
the particular ship.
A dial telephone system consists of a group
of telephones with lines so arranged at a central
point that any two telephones in the system can
be interconnected. In a dial telephone system,
the connections between the telephones are com-
pleted by remotely controlled switching mech-
anisms.
The switching mechanisms of a dial telephone
system are controlled at the calling telephone
by a dial on the telephone instrument. When the
dial is operated, a series of interruptions, or
impulses, occur in the current flowing in the
line circuit. The number of impulses sent out
by the dial corresponds to the digit dialed. These
impulses cause the automatic switches to operate
and to select the called telephone.
A typical dial telephone system (fig. 10-13)
consists of: telephone station equipment, made
up of telephone instruments which may receive
or initiate calls; dial telephone switchboard
equipment that includes the switching necessary
to interconnect the line stations; power equip-
ment that furnishes normal and emergency power
for the system; and accessory equipment used
to interconnect the ship's telephone equipment
with shore telephone equipment when the ship
is in port.
TELEPHONE STATION
EQUIPMENT
The telephone station equipment (sometimes
referred to as line stations) consists of different
types of telephone instruments. The telephone
instrument is a unit which transmits and receives
speech and signals the desired station. It
comprises a transmitter, receiver, dial and
ringer. The transmitter changes sound into an
undulating current which is sent over anelectrical
circuit. The receiver changes the undulating
current back into sound. The dial, when operated,
causes a series of interruptions (impulses) in the
current flowing in the line circuit. The ringer
provides an audible signal when the station is
called.
PUSHBUTTON
27.292
Figure 10-12. Simple call-bell system.
Types of Telephones
The types of telephones furnished with dial
telephone systems are illustrated in figure 10-14
The types differ mainly in the form in which
the components are assembled. The components
perform the same function, but the enclosure
and method of mounting for each type is of
special design.
The TYPE A desk set telephone (fig. 10-1 4A)
is installed in staterooms, cabins, offices, and
206
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
TELEPHONE
STATION
EQUIPMENT
SHORE LINES
DIAL TELEPHONE
SWITCHBOARD
EQUIPMENT
I
ACCESSORY
EQUIPMENT
I
1 I
I I
I L.
POWER
BOARD
M~G
SET
BATTERY
POWER EQUIPMENT
J
I
| i SHIP'S POWER SUPPLY
Figure 10-13. Block diagram of the dial telephone system.
7.76(140B)
similar stations. The desk set consists of a
phenolic case (containing the ringer, dial and
other working parts), a handset, and connecting
cord with a terminal block for making the line
connections.
The TYPE F bulkhead telephone (fig. 10-14B)
can be installed in any station except those on
weather decks. The type F telephone is a non-
watertight unit designed for mounting on a bulk-
head or on the side of a desk. It consists
essentially of a metal housing on which are
mounted the handset, dial, and ringer. The line
connections are made at a terminal block inside
the housing.
The TYPE C splashproof telephone (fig. 10-
14C) is installed at stations on weather decks
and at any other stations exposed to moisture.
The type C telephone is designed for bulkhead
mounting and consists essentially of a metal
housing on which are mounted the handset and
dial which axe enclosed in a splashproof box.
The TYPE G telephone (fig. 10-14D) is used
in all new dial telephone system installations
and is used to replace the type A, C, and F
telephone of older installations as they wear
out. The basic type G telephone is available
with three different enclosures which adapt it
to use in place of the A, C or F telephones.
DIAL TELEPHONE
SWITCHBOARD
EQUIPMENT
The dial telephone switchboard is the switching
center of the dial telephone system . Mounted in
this switchboard are all telephone switching
mechanisms, control circuits, part of the testing
equipment, and most of the supervisory alarm
signals.
These switch mechanisms automatically per-
form the following functions:
1. Locate a station desiring to make a call.
2. Respond to dial impulses and extend the
calling station to the called station.
3. Ring the called station and, if necessary,
select between the two parties on a party line.
4. Supply various tones, such as dial tone,
busy tone, and ring-back tone, as required.
At present there are at least four major
types of dial telephone switchboard equipment
employed in the Navy. In this section two of
these types of equipment, the Automatic Electric
207
SHIPBOARD ELECTRICAL SYSTEMS
A- TYPE A {DESK SET) TELEPHONE
C-TYPE C {SPLASHPROOF) TELEPHONE
6- TYPE F {BULKHEAD TYPE) TELEPHONE
D-TYPE {G) BULKHEAD TELEPHONE
Figure 10-14. Telephone station equipment.
7.83
208
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
and the Marine Dialmaster, plus their basic
operating principles will be discussed.
Automatic Electric
Switchboard Equipment
Until recently the Automatic Electric Switch-
board equipment (figs. 10-15 and 10-16) was the
only type employed aboard UJ3. Navy surface
ships* This equipment was furnished in various
sizes capable of servicing from 50 to more than
600 telephone stations* The Automatic Electric
Switchboard equipment utilizes the Strowger
switch as the basic switching element to perform
the functions required of a dial telephone switch-
board.
SWITCHING. The Strowger switch (fig. 10-
17) is an electromechanical device which, as
used in the Automatic Electric Telephone System,
extends the connection from the calling to the
called telephone. The assembly of fixed electrical
contacts, arranged in ten levels, generally with
ten sets of contacts to a level, is called a wire
bank. The electrical members which make contact
with the selected set of contacts in the wire
banks are called wipers. These wipers are
connected to the switch shaft.
The switch mechanism elevates the shaft
vertically (therefore the wipers) and then rotates
the shaft (and wipers). Because of this vertical
and rotary motion, the Strowger switch is often
referred to as a two-motion switch.
The Strowger switch is the basic switch of
the system being used as a finder, connector,
and selector, in each case employing slightly
different electrical and mechanical variations.
Figure 10-17 shows the mechanical elements
common to all Strowger switches. As one of
its variations, the finder switch has an additional
set of vertical wipers connecting to a vertical
bank.
LINE GROUPING AND NUMBERING. The
basic system of grouping provides for a maximum
of 100 lines, as shown in figure 10-18. The
horizontal dashes represent 100 pairs of metallic
contacts* There are 10 horizontal levels and
10 sets of contacts in each levelo Thus, the
tens digit of the called number represents the
level, whereas the units digit represents the
individual pair of contacts in the leveL
Numbers beginning with 1 are in the first,
or bottom, level, numbers beginning with 2
are in the second level, and so on. This arrange-
ment causes the digit to be used to represent
10 steps so that the 10th, or top, level is indicated
by the symbol for zero. Also, the 10th pair of
contacts in each level is indicated by the symbol
for zero. Groups of 10 lines are referred to as
lines 11-10, 21-20, 31-30, and so forth. The
first 10 lines consist of 11-10, and the last
10 consist of 01-00.
Each pair of metallic contacts is connected
to a pair of wires that lead to a particular
telephone. These contacts are actually contained
in a Strowger switch, arranged in the arc of a
circle with the vertical rows parallel to the axis
of the cylinder. The entire assembly of contacts
is called a wire bank.
These wire banks are commonly referred to
by the type of switch with which they are asso-
ciated, such as finder bank, connector bank, etc.
A pair of metallic wipers mounted on the
shaft of the Strowger switch is shown (fig 10-18)
at the lower left-hand corner of the wire bank.
These wipers are moved under the control of
the dial on the calling telephone. For example,
if the calling telephone calls telephone No. 32,
when digit 3 is dialed, the wipers step UP to the
third level in the wire bank. When digit 2 is
dialed, the wipers rotate IN 2 steps on the
third level to connect the calling telephone with
telephone 32. Likewise, to connect the calling
telephone with telephone 67, the wipers step UP
6 steps and then rotate IN 7 steps.
BASIC 100-LINE SYSTEM The system de-
scribed with reference to figure 10-18 is not
practical because only the calling telephone
can originate calls Therefore, the basic 100-line
system (fig. 10-19) was implemented. Each tele-
phone is connected to the wipers of its own
connector switch. The wiper of each switch can
be stepped up and rotated in, under the control
of the dial of the calling telephone. One connector
bank with its wipers and the mechanism necessary
to step the wipers up and in constitute a CON-
NECTOR SWITCH, A connector switch is referred
209
SHIPBOARD ELECTRICAL SYSTEMS
CONNECTOR SWITCHES
1 5
TEST- LINE JACK'
CONNECTOR SWITCHES
6-10
AUXILIARY
TEST PANEL
CONNECTOR SWITCHES
1115
Figure 10-15. Connector cabinet, Automatic Electric Telephone Switchboard.
210
27.389
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
RINGING
MACHINE NO. 1
RINGING
MACHINE NO. 2
POWER
CONTROL PANEL
TERMINAL BLOCK
RINGING
MACHINE
CONTINUE NO. 1
RINGING MACHINE
TRANSFER 8
TEST SWITCHES
RINGING
MACHINE NO. 2
TEST SET
CONNECTOR
TRUNK AND
MISCELLANEOUS
TERMINAL BLOCK
27.390
Figure 10-16. Automatic Electric Telephone Switchboard miscellaneous equipment cabinet.
SHIPBOARD ELECTRICAL SYSTEMS
VERTICAL MAGNET -
SWITCH SHAFT
VERTICAL BANK
FOUND
I ONLY ON
( FINDER
VERTICAL WIPER I SWITCHES
WIPER CORDS
WIRE BANK
WIPERS
Figure 10-17. Strowger switch.
140.129
to as a NUMERICAL type Strowger switch because
it operates under the control of dial impulses.
For simplicity, only 3 of the 100 telephones
with their associated connector switches are
shown in figure 10-19
Telephone 32 is connected to the wipers of
connector 32. Telephone 32 also has an appearance
in the bank of each connector that is, it is
multiplied to contact 32 in all of the connector
banks. Telephone 67 terminates in wiper con-
nector 67 and is likewise multiplied to its
associated contact 67 in all of the connector
banks. This multiple arrangement of the con-
nector banks permits any telephone to call any
other telephone in the system.
For example, to call telephone 89 from
telephone 32, remove the handset from the
cradle at telephone 32 and dial the digits 8 and
9. When 8 is dialed, the wipers of the connector
switch 32 step up to the eighth level and when
9 is dialed, the wipers rotate into the bank and
come to rest on the ninth contact of that level.
This action completes the connection to telephone
89.
LINE FINDINGo The 100-line connector
system described with reference to figure 10-19
requires an individual connector switch for each
line in this system. As the connector is a
relatively expensive switch, this system is not
economical because the average telephone is used
to make calls only a short time each day with
the result that the corresponding connector switch
remains idle during the remainder of the time.
Line finding permits service to a large group
of lines by a smaller number of switches used
in common by all lines in the group. The line
finding principle is illustrated in the diagram
of the two switches shown in figure 10-20.
212
01 02 0.3 0405 06 07 08 09 00
8828384858687888980
71 7273747576T77879 70
62 63 6465 66 ffi 68 69 60
WIPERS
7 58 59 50
17 48 49 40
57 38 39 30
17 28 29 20
7 18 19 10
w
CALLING
TELEPHONE
32) (67
<~S \Ls
TELEPHONES
7,77(27C)
Figure 10-18. Wire bank numbering*
One is called the FINDER SWITCH and the other
is the previously mentioned CONNECTOR
SWITCH. One finder bank with its wipers and
the mechanism necessary to step the wipers
up and in constitute a FINDER SWITCH. A
finder switch is referredtoasaNONNUMERJCAL
type Strowger switch because its operation is
automatic and not under the control of dial
impulses. Although four telephones are shown,
actually there are 100 telephones connected
to the finder bank e
To call telephone 00 from telephone 11,
remove the handset from the cradle at
telephone 11. The finder switch (fig,
10-20) automatically steps its wipers up
to the first level and rotates one step
in, stopping on contact 11. Thus the
calling telephone is extended through to
the wipers of the connector switch. When
the digits and are dialed, the
wipers of the connector switch step up
to the tenth level and rotate 10 steps
in, completing the connection between tele-
phones 11 and 00.
BASIC 100 - LINE FINDER- CONNECTION
SYSTEM. The system described with reference
100 LINES
TO
100 TELEPHONES
CONNECTOR 32
WIPERS
WIPERS
CONNECTOR 67
CONNECTOR S9
WIPERS
7.78(27C)
Figure 10-19 Basic 100-line system.
to figure 10-20 is equipped with one finder switch
and one connector switcho Hence, only one con-
versation is possible at any one time because
each conversation requires one finder and one
connector to complete and hold a connection
between the calling and the called telephones.
The 100-line finder-connector system is shown
in figure 10- 21 A. Each finder switch is perma-
nently tied stem to stern with a connector
switch. In other words, the finder faces backward
ready to find any line that originates a call,
whereas the connector faces forward ready to
connect to the dialed line. Such a combination
213
SHIPBOARD ELECTRICAL SYSTEMS
TERMINALS-
/
SHAFT
rr
^WIPE
:R
^ N 10
i'' ^ x ^"
FINDER SWITCH
PONNECTOR SWITCH
Figure 10-20. Basic 100-line finder-connector system.
7.78(140B)
of finder and connector is called a FINDER-
CONNECTOR LINK. One finder-connector link
is required for each of the conversations that
are to be held simultaneously* There are 15
finder-connector links in the 100-line Automatic
Electric Telephone System.
Each of the 100 lines is connected to each
finder bank. Hence, any idle finder is capable
of stepping up and rotating in to locate any one
of the 100 lines that originates a call. Also,
each of the 100 lines is connected to each
connector wire bank. Hence, under control of
dial impulses from the calling telephone, the
connector can step up and rotate in to complete
a connection to any one of the 100 telephones.
Look again at figure 10-21A* To call tele-
phone 89 from telephone 32, remove the handset
from the cradle at telephone 32. An idle finder
such as finder 1, steps up, rotates in, and stops
on contact 32. The connection is now extended
through to the connector associated with the
finder, in this case connector 1, and the dial
tone is received by the calling telephone. The
DIAL TONE is a signal to the person making
the call to dial the number of the called tele-
phone. When digits 8 and 9 are dialed, the wipers
of the connector switch step up, rotate in, and
stop on contact 89.
The connection is now completed from tele-
phone 32 through finder-connector link 1 to tele-
phone 89 . The connector switch now te sts telephone
89 and, if it is not in use, ringing current is sent
out to operate the ringer at telephone 89. If
telephone 89 is in use, a busy signal is returned
to the calling telephone.
A complete 100-line finder-connector system
is shown in figure 10-21B, The finder and con-
nector banks are each represented by 10 horizontal
lines. The rectangles at the top of the finder and
connector banks represent the switch mech-
anisms. One line relay is associated with each
line, whereas the finder control and the dis-
tributor equipment is common to all lines a
To call telephone 67 from telephone 32,
remove the handset from the cradle at telephone
32 This action closes contacts within telephone
32 which causes line relay 32 to operate. Line
relay 32 in operating marks the position of
line 32 in the finder banks.
When the line relay operates, it also sends
a START SIGNAL to the finder control and
distributor equipment which, in turn, starts apre-
selected idle finder in search of the calling
line.
The finder control and distributor equipment
at this time automatically preselects the next
214
Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
iES
)NES
v-
r
r
t:
)-
r
<
FINDER 1
TX
< C
DNNECTOR
1
I
>
:J
r
FINDER 2
r c
ONNECTOR
2
!>
* *
*
. ^
*
<
^i
r
FINDER 3
jf r
ONNECTOR
3
MULTIPLED TO OTHER FINDER-CONNECTOR LINKS AS
REQUIRED
(A)
N6
DNE
FINDER
CONTROL
AND
DISTRIBUTOR
CALLED
TELEPHONE
(6?)
- FINDER] [CONNECTOR
=
LINE
KULAK 041
7. 80 (140 A)
re 10-21. Complete 100-line finder-
connector system.
finder to have it ready to search for the
incoming call.
'he selected finder that is searching for line
Lnds it and extends the connections through
e connector switch.
Line relay 32 in operating also makes line
32 busy at the connector banks to guard against
intrusion from any incoming call.
The connector switch returns a dial tone
to the calling telephone and the call proceeds
as previously explained.
EXPANDING THE 100-LINE SYSTEM, The
100-line finder-connector system can be expanded
to service as many as 200 telephones through the
use of a party line system, made possible
through the use of an additional switch called
a minor switch. The minor switch has rotary
motion only and is mounted with the connector
switching mechanism. As pictured in figure
10-22 the minor switch bank consists of 10
sets of contacts over which the wipers may
step under control of the dial. This switch is
a one-function auxiliary switch which rings one
or the other of two telephone stations on a two-
party line.
With the minor switch arrangement an ad-
ditional digit is added to all phone numbers. In
this type equipment, telephones having the first
digit of 1, 2, 3, 4, 5, 6, 7, 8, or will receive
ring current over their positive line, while those
whose first digit is 9 will receive ring current
over their negative line. The arrangementpermits
the selective ringing of either telephone station
of a two-party line. As an example, if you dial
number 932, the ringer at telephone station
932, which is connected to operate with negative
ring voltage, will operate. The ringer at telephone
station 232, which is on the party line with
telephone station 932, will not operate because it
is connected to operate on positive ringing voltage.
BASIC FINDER-SELECTOR-CONNECTION.
The system described with reference to figure
10-21 has a capacity of 100 lines. In systems
of 200 lines or more, a SELECTOR SWITCH
is connected between the finder and connector
switches, as shown in figure 10-23. The selector
is similar in mechanical construction to both
the finder and connector. It has a wire bank,
wipers, and a two-motion switch mechanism.
The selector faces the called line the same
as does the' connector. The selector selects the
"hundreds" group of lines. From then on, a
connector selects both the "tens" group of
lines and the "units" line in that group. Note
that the lines (fig. 10-23) are divided into groups
SHIPBOARD ELECTRICAL SYSTEMS
ROTARY
MAGNET
RELEASE
MAGNET
ROTARY ARMATURE
RESTORING SPRING
BANK CONTACT
TERMINAL
OFF NORMAL
SPRING
ASSEMBLY
WIPER ASSEMBLY
RESTORING SPRING
RELEASE ARMATURE
RESTORING SPRING
Figure 10-22. Minor switch.
140.76
of lOOo Two such groups are shown, the 200
group with 100 lines and the 600 group with
100 lines. Each group has a corresponding group
of connectors which have their banks multiplied
together.
Note that each finder switch is tied stem to
stern with a selector switch instead of being
tied to a connector switch, as in the 100-line
capacity system,, One finder-selector-connector
link is required for each conversation that is
to be held simultaneously with other conver-
sations. The connector switch always operates last
and selects the "tens" group of lines and the
* 'units" line within the group.
To call telephone 673, remove the handset
from the cradle at the calling telephone. An idle
216
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
CONNECTOR
GROUP
^
WORM WHEEL
AC END
100 TELEPHONES
IN THE
"600" GROUP
100 TELEPHONES
IN THE
"200" GROUP
7.82(27C)
Figure 10-23. Basic selector system,,
finder searches and extends the calling line to
the selector switch associated with that finder.
The selector returns a dial tone to the calling
telephone. When the "hundreds" /digit 6isdialed f
the selector wipers step to the sixth level and
automatically rotates in to a contact that is
attached to an idle connector; this extends the
call through to the wipers of a connector. When
digits 7 and 3 are dialed, the connector steps up
7 levels and rotates in three steps to complete
the call.
ALARM SYSTEM. The Automatic Electric
Dial Telephone switchboard contains an alarm
system which warns watch personnel when con-
ditions within the switchboard are not normal.
The alarm system consists of a common audible
buzzer and lamps that provide a visual indication.
Alarms sound if power is lost, if fuses are blown*
if problems develop within finder sand connector s,
or if the handset of telephone stations are left
off the hooko Conditions which cause the last two
alarms listed usually result in the loss of a
finder-connector link which limits the number of
simultaneous conversations that the switchboard
is capable of handling.
Watch personnel should be alert to immediately
correct the conditions that cause an alarm.
RINGING MACHINES. The Automatic Elec-
tric Dial Telephone switchboard contains two
ringing machines (fig, 10-24) 9 which are small
motor-generator sets. These motor-generator
sets produce dial tone* busy tone, and ring and
ring-back voltages for the dial telephone system*
The second ringing machine provides a backup
if the first machine fails P
TERMINAL
STRIPS
WORM
DC END
FILTERS
140.82
Figure 10-24 Ringing machine (covers removed).
POWER EQUIPMENT The power equipment
includes a motor-generator set (fig. 10-25) and a
storage battery The motor-generator set and the
storage battery are connected in parallel and
supply approximately 51 6- volt d.c. power to
operate the automatic switchboard equipment,
including the ringing machine sand alarm systems.
The motor-generator set receives operating
power from the ship's 440-volt 60-Hz, 3-phase
power supply via the nearest 1C switchboard.
A reserve supply of energy is maintained in
the storage battery so that the telephone system
will continue to operate if the ship's power
supply fails.
ACCESSORY EQUIPMENT. The accessory
equipment (furnished in some ships) includes
an attendant's cabinet (fig. 10-26) which is a
small manual switchboard. The attendant's cabi-
net provides an interface between the ship's
telephone system and another telephone system
to accomplish calls to and from shore exchanges
when the ship is in port, and calls between
ships when they are nested.
MARINE DIALMASTER
DIAL TELEPHONE
SWITCHBOARD EQUIPMENT
The Marine Dialm aster dial telephone switch-
board equipment is a relatively recent develop-
ment. The equipment is modular in construction
217
SHIPBOARD ELECTRICAL SYSTEMS
FILTERS
INPUT TERMINALS
OUTPUT TERMINALS
MOTOR
LEADS
SHUNT
RESISTOR
COMPARTMENT
Figure 10-25. Motor-generator set (cover opened).
140.87
and it is much more compact than the previously
discussed Automatic Electric Dial Telephone
equipment. For example: the Marine Dialm aster
100-line dial telephone system occupies less than
half the space required for an Automatic Elec-
tric system with the same capabilities. The
compactness of the system is due to modular
construction techniques. All electromechanical
switching devices and solid-state circuits, as
well as all power equipment, are mounted on a
single equipment rack. The Marine Dialm aster
dial telephone equipment is furnished in two
basic systems. One system, the MDM/700, is
furnished as a 200-line system capable of being
expanded in 100-line increments to a maximum
of 700 lines. The other system, the MDM/100-
15, is a 100-line system which will be discussed
as a comparison to the previously described
Automatic Electric 100-line system.
The MDM/100-15 dial telephone system per-
forms the same basic function as the previously
described Automatic Electric System. The pri-
mary difference is that the MDM/100-15 system
employs XY-Universal switches to perform the
functions that the Strowger switch performs
in the Automatic Electric System. The system
is comprised of one switchboard cabinet and in
some cases an attendant's cabinet. The MDM/
100-15 system can be used with the type A,
C, F, or G telephone station equipment.
MDM/100-15
Switchboard
The switchboard consists of one rack of
equipment shock-mounted in a rigid cabinet
assembly. The cabinet circuit modules, which
are accessible through front and rear doors,
plug into the frame-jack panel and contain all
the switching circuits necessary to operate the
system . Two XY-Universal switches are asso-
ciated with each of the 15 link circuit modules.
These switches are mounted in cells on the
front of the frame, and they plug into the asso-
ciated link circuit modules (fig. 10-27). The
line connection panels, mounted directly on the
switchboard frame (fig. 10-28), provide the means
to connect the switchboard to the ship's telephone
station cables.
SWITCH COMPONENTS, In the MDM/100-15
system, the XY-Universal switch (fig. 10-29)
functions as a finder and as a connector and
provides the means to establish connections
from the calling telephone station to the called
telephone station. The XY-Universal switch is
a two-motion, remote-control device which may
be operated under the control of a dial or auto-
matically pulsed from associated control cir-
cuitry.
218
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
SHORE TRUNKS
AND
TERMINAL
BLOCK
OO'QOOQ.O
KEY
PANEL
HEADSET
RECEPTACLE
LOCAL TRUNKS,
FUSE PANEL,
AND
TERMINAL
BLOCK
Figure 10-26. Attendant's cabinet.
219
140.79
SHIPBOARD ELECTRICAL SYSTEMS
LINK CIRCUIT
MODULE
LINK ALLOTTER
CIRCUIT MODULE
LEVEL DETECTOR
CIRCUIT MODULE
COMMON CONTROL
CIRCUIT MODULE
FINDER XY SWITCH
CONNECTOR XY SWITCH
FINDER XY SWITCH
CONNECTOR XY SWITCH
XY SWITCH
RETAINING DOOR
MONITOR AND
DISTRIBUTION PANEL
CIRCUIT MODULE
POWER SUPPLY
CIRCUIT MODULE
RING VOLTAGE
GENERATOR
CIRCUIT MODULE
Figure 10-27. MDM/100-15 switchboard cabinet, front view.
220
27.391X
Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
SHIP LINE MODULES
WIRE CHANNEL
CONNECTION PANEL
POWER SUPPLY
CIRCUIT MODULE
RING VOLTAGE
GENERATOR
CIRCUIT MODULE
SHORE TRUNK MODULES
CONTROL MODULE,
LINE CONNECTION
PANELS
CABLE ACCESS
CHANNEL
REAR JACK
PANEL
Figure 10- 28 , Switchboard cabinet, rear view.
221
SHIP'S CABLE
ENTRY PANEL
27.392X
SHIPBOARD ELECTRICAL SYSTEMS
P1U6
RELEASE MAGNET
X MAGNET
XX-X WIPERS
TtR,S t HS
WIPERS
Y MAGNET
X CARRIAGE
Y CARRIAGE
Figure 10-29. XY-Universal switch.
140.165
The XY-Universal switch can make electrical
contact with any of 100 sets of contacts, taking
two motions to accomplish the connection. The
switch is mounted in a horizontal plane. The
switch carriage moves first in the X-direction
(left to right parallel to the wire bank) and then
in the Y-direction (into the wire bank). When
mounted in the switchboard, the XY-Universal
switch is located adjacent to a wire matrix,
or wire bank. The wire bank runs the length
of the switchboard and serves as the contacts
for the wipers of all 30 XY-Universal switches
in the system.
The XY-Universal Switch. The main com-
ponents of the XY-Universal switch (fig. 10-29)
are an X- stepping magnet, a Y- stepping magnet,
a release magnet, spring pileups, and associated
mechanical drive hardware. The switch steps
first in the X-direction, controlled by a series
of pulses extended to the X-stepping magnet.
Each time the magnet operates, the wipers
advance one step in the X-direction. The Y-
stepping magnet functions in a similar manner
to drive the wipers in the Y-directioft, which is
into the wire bank.
There are 30 XY-Universal switches used
in the MDM/100-15 system, 15 as finders and
15 as connectors.
The Wire Bank. The wire bank associated
with the XY-Universal switch is actually made
222
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
up of six smaller wire banks: four 10 by 10
wire banks and two 1 by 10 wire banks. The
10 by 10 wire banks are used with the four
wires associated with each telephone line. These
four wires are the tip (T) and ring (R) for
transmission, and the sleeve (S) and helping
sleeve (HS) for supervisory and switching. The
1- and 10-wire banks (XX and X) indicate elec-
trically the X-position of the wipers when the
wipers are stepped in the X-direction. Each
of these banks is associated with its own par-
ticular wiper on the XY-Universal switch; hence,
the switch wipers are referred to as the T,
R, S, HS, and XX-X wipers or banks. Figure
10-30 is a simplified diagram of a 10 by 10
wire bank (as seen from above) with its asso-
ciated wiper.
The wire banks run the length of the switch-
board and are associated with the same wiper
for each of the other 30 XY-Universal switches
in the system (fig. 10-31). The X-motion of the
switch locates the wiper at a position (or bank)
opposite the proper section of the wire bank.
The Y-motion of the switch positions the wiper
into the bank to establish the connection at the
proper point*
20
30 40
50
60
70 80
90
100
O
O
O
O
O
O
00
190
O
O
O
o
O
o
09
180
O
O
O
o
08
170
O O
O
O
O
o
O
o
07
160
O
O
O
o
O
o
06
150
o
o *>
O
O
O
o
O
005
WIPER
140
o
JO
O
O
O
04
IN POSITION
5 OF LEVEL 4
130
o 4
O
O
O
O
o
03
STATION 45
120
o
o
o
O
O
o
o
02
11
o
o
O
o
o
o
o
o
01
V
21
31
41
\
51
61
71
81
91
I
U WIPER
AFTER
1st
SET OF
IMPULSES -
K
hk.
1 DRIVEN TO POSITION 4
-WIPER IN ORIGINAL (NORMAL) POSITION
NOTE: DIRECTION OF WIPER MOVEMENT INDICATED BY *>
140.167
Figure 10-30. Wire bank and associated XY-
Universal switch wiper, simplified diagram.
FINDER-CONNECTOR LINKS. As previ-
ously stated, the MDM/100-15 system contains
30 XY- switches, 15 as finders and 15 as con-
nectors. These finders and connectors are con-
nected back to back, the same as the finders
and connectors of the Automatic Electric System,
through 15 link circuit modules as shown in
figure 10-27. The link circuit module ties the
linefinder and connector together and pro-
vides control functions for both switches. The
linefinder XY-Universal switch, connector XY-
Universal switch, line circuit module, and their
portion of the common wire bank comprise one
finder-connector link.
Link Allotter.- The link allotter performs
the same function in the MDM/100-15 as the
finder distributor of the Automatic Electric
System assigns the next idle finder-connector
link to the calling party.
System Operation
Basically, the operation of the MDM/100-15
is very similar to that of the Automatic Electric
System. Assume that telephone station 12 initiates
a call to telephone station 95. When the calling
telephone's handset is removed from the hook-
switch of telephone 12, a signal is produced
that causes the allotter to assign an idle finder-
connector link to the calling telephone. As soon
as an idle link is assigned, the finder of that
link begins to search for the calling telephone
line. In this case the finder XY-Universal switch
will move 1 step in the X-direction and 2 steps
in the Y-direction and the dial tone will return
to the calling telephone station at this time.
The number of digits that the calling party
must dial depends on whether the system is set
up to provide party line ringing (negative and
positive ringing voltage). If party ringing is
to be used, three digits are required, if not,
only two digits are required. Let us assume
that we are calling telephone 95 and that party
ringing will not be used. Therefore, it is
necessary to dial only two digits to reach the
called telephone station. When the digits 9 and
5 are dialed at the calling telephone, the con-
nector XY-Universal switch steps 9 spaces in
the X-direction and 5 spaces in the Y-direction.
A busy test is then performed on line 95. If
the line is busy, the busy tone will be returned
to the calling telephone station. If the line is
223
SHIPBOARD ELECTRICAL SYSTEMS
DUST COVER
X-XX BANK
TAND R
BANK
S AND HS
BANK
SWITCH
CELL
SWITCH
CELL
DOOR
Figure 10-31. XY-Uni versa! switch cell and wire banks*
140.168
not busy, ringing will be extended to signal the
called party.
Power and Signaling
Equipment
The MDM/100-15 utilizes solid-state devices
to provide its d.c, and ringing voltages. These
devices are contained within the switchboard
cabinet*
Attendant's Cabinet
The MDM/100-15 installations may be
equipped with attendant's switching circuitry
to provide attendant-assisted ship-to-shore com-
munications. This circuitry is mounted in the
switchboard cabinet (fig. 10-28) and consists
of four ship line modules (one for each ship
line), four shore line modules (one for each
shore line), and one control module. The
attendant's switching circuit is controlled from
a remotely located attendant's cabinet (fig. 10-32).
Since all of the attendant's switching equip-
ment is mounted in the switchboard cabinet,
the attendant's cabinet performs only the func-
tions of a standard telephone with pushbutton
control of switching modules to seize and inter-
connect ship lines and shore lines. The attendant's
cabinet is not much larger than a standard
type-G telephone set and can be mounted on
a desk or bulkhead, or flush-mounted in a
suitable panel*
224
Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS
>
oo> o
140.164
Figure 10-32. Attendant's cabinet.
PES OF CALLS
Most of the shipboard dial telephone systems
'e designed to permit a wide variety of tele-
x>ne calls to meet a variety of needs. These
pes of calls are summarized below.
Regular local service is the routine call
lerein the caller dials the desired number and
iceives either a ring-back or a busy tone in
s receiver. If the called station is manned
id if the phone is not in use, the call should be
mpletedo If a busy tone is received, the calling
tone must redial the number.
Executive service is that additional feature
' which a priority telephone will cut in on a
innection which has already been made to the
inber which he wishes to reach. An executive
tone always reaches the party called, even when
e line is busy.
Emergency service is a specifically designed
ature by which any caller, who dials a special
imber (usually 211), will reach the station at
which the Officer of the Deck has posted his
watch, whether the Quarterdeck or the Pilot-
house. The call will be completed regardless of
whether the line is open or busy. A switch con-
trolling the recipient phone (Quarterdeck or
Pilothouse) is located on the telephone switch-
board.
Ship to Shore Call is a call connected man-
ually through the attendant's cabinet. To complete
this call (possible only when in port and con-
nected), the caller dials the attendant's cabinet,
and the ship's operator extends the call through
to the shore facility.
Shore to Ship Call is also a feature conducted
through the attendant's cabinet. Here again, the
ship's operator completes the call through the
manual facilities available to him at his station.
On many installations ship's telephone lines
37, 38, 39, and 30 are reserved for the manual
switchboard.
Additionally, the ' 'hunt the not-busy feature"
is employed in cases where a series of numbers
serve the same location. In this type arrangement,
as in the case of the attendant's cabir^pt, assume
that line 37 is in use and a second caller dials
the attendant's cabinet number 37. The call will
be shifted automatically to line 38. This "hunt"
feature continues until the call is completed
or until the caller receives busy from the last
in the series of so connected lines (30).
SAFETY
Potentials as high as 450 VAC may be en-
countered while your men work on dial telephone
equipment. Your men must practice all standard
precautions when working around high voltages,
rotating machinery, and batteries.
An additional precaution for dial telephone
systems that you should observe is that all
shore telephone lines must be connected to a
lightning arrestor box located on the weather
decks before the line is routed to the telephone
equipment. The lightning arrestor boxprotects the
telephone operator and the telephone equipment
in case lightning should strike the incoming
telephone lines.
DIAL TELEPHONE
SYSTEM MAINTENANCE
Aboard ship, every attempt should be made
to maintain a telephone school graduate with
an NEC for the type of system installed. However,
this is not always possible and should not be used
as an excuse to let the system deteriorate.
SHIPBOARD ELECTRICAL SYSTEMS
The knowledge necessary to operate and
maintain this sy stein can be obtained from a
combination of PQS, OJT, and the manufacturer's
technical manual.
Dial telephone system maintenance includes
periodic tests and inspections, lubrication, clean-
ing, troubleshooting, and repair. Test equipment,
special tools, special lubricants, and charts
are provided with each system, and detailed
maintenance instructions are included in PMS
and the manufacturer's technical manual.
Cleanliness is essential because of the low
voltages and currents involved. Dirt and dust
can cause insulation failures and high resistance
or partially open contacts.
The adjustable parts of the relay sand switches
are delicate and require the use of special adjust-
ment tools. Adjustment of a switch or relay
should not be attempted until it has been definitely
determined that adjustment is necessary. When
adjustment is necessary, the manufacturer's
instructions must be followed carefully*
226
CHAPTER 11
AMPLIFIED VOICE SYSTEMS
Many types of voice communication facilities
are needed to effectively control and administer
a naval vessel during the course of each day.
The telephone systems, described in the previous
chapters, fulfill many of these needs, but their
effectiveness is limited in high noise level areas
and where it is desired to transmit a command
or information to several listeners simultan-
eously. Amplified voice systems are used to
overcome some of the shortcomings of telephone
systems.
Amplified voice systems are used in a wide
variety of forms aboard Navy ships such as
public address and intercommunication (inter-
com) systems. Other variations of amplified
voice systems that are employed are tape re-
corders, sound motion picture projection equip-
ment, and ship's entertainment equipment.
ANNOUNCING AND
INTERCOMMUNICATING
SYSTEMS
The general purpose of shipboard announcing
and intercom systems, circuits IMC through
59MC, is to transmit orders and information
between stations within the ship by amplified
voice communication by either a central ampli-
fier system, or an intercommunication system.
A central amplifier system is used to broadcast
orders or information simultaneously to a number
of stations. An intercom system is used for
two-way transmission of orders or information.
Each announcing and intercom system in-
stalled aboard ship is assigned an 1C circuit
designation in the MC series. The Chief of
Naval Operations authorizes these MC circuits
for each class of vessel, based on size, com-
plement, function, and operational employment.
Authorized 1C announcing circuits are listed
in Table 11-1, according to importance and
readiness. These systems, however, are not all
installed in any one ship.
CENTRAL AMPLIFIER
ANNOUNCING SYSTEMS
Central amplifier announcing systems are
designed to furnish amplified voice communica-
tion and, in some cases, alarm signals to the
various loudspeakers located throughout the ship.
These systems transmit the spoken word or
signal from a station, amplify the signal at a
central amplifier, and radiate the signal from
the loudspeaker or loudspeakers located in re-
mote areas.
As you can see in table 11-1, several of the
MC systems are of the central amplifier type.
The size of these systems ranges from the IMC
system on an aircraft carrier to the very small
by comparison, 29MC system on an old class
destroyer. In many instances, the control and
amplification facilities of several different MC
systems may be combined. As an example:
if a ship has a 6MC- system installed, it is
usually combined with the IMC system.
1MC-6MC Announcing
Systems Equipment
The combined 1MC-6MC systems installation
provides general shipboard announcing (circuit
IMC) and intership announcing (circuit 6MC)
facilities. Additionally, a means of broadcasting
various ship's alarms is provided in conjunction
with, and as part of, circuit IMC. The typical
1MC-6MC installation consists of: alarm contact
makers, microphone control stations, loud-
speakers, visual alarm indicators and the control/
amplifier equipment. Figure 11-1 is a block
227
SHIPBOARD ELECTRICAL SYSTEMS
Table 11-1. Shipboard Announcing Systems
Circuit
System
Importance
Readiness Class
*IMC
General
V
1
*2MC
Propulsion plant
V
1
*3MC
Aviators'
V
1
4MC
Damage Control
V
1
*5MC
Flight Deck
sv
2
*6MC
Inter ship
sv
1
7MC
Submarine Control
V
1
BMC
Troop administration and control
sv
2
*9MC
Underwater troop communication
sv
2
*10MC
Dock Control (obsolete)
sv
1
*11-16MC
Turret (obsolescent)
sv
3
*17MC
Double Purpose Battery
(obsolescent)
sv
3
18MC
Bridge
NV
2
19MC
Aviation Control
sv
2
*20MC
Combat Information
(obsolescent)
sv
1
21MC
Captain 1 s Command
sv
1
22 MC
Electronic Control
NV
I
23MC
Electrical control
sv
I
24MC
Flag Command
sv
1
25MC
Ward Room (obsolescent)
NV
4
26MC
Machinery Control
SV
1
27MC
Sonar and Radar Control
sv
1
*28MC
Squadron (obsolescent)
NV
4
*29MC
Sonar Control and Information
SV
2
30MC
Special Weapons
sv
2
31MC
Escape trunk
sv
2
32MC
Weapons control
sv
3
33MC
Gunnery Control (obsolescent)
sv
3
34MC
Lifeboat (obsolescent)
sv
1
35MC
Launcher Captains'
sv
1
36MC
Cable Control (obsolete)
NV
4
37MC
Special Navigation (osbolete)
sv
2
38MC
Electrical (obsolete)
NV
1
39MC
Cargo Handling
NV
4
40MC
Flag Administrative
NV
1
4 IMC
Missile Control and Announce
(obsolete)
SV
3
42MC
CIC Coordinating
SV
2
43MC
Unassigned
44MC
Instrumentation Space
NV
1
45MC
Research operations
NV
1
*46MC
Aviation Ordnance and Missile
Handling
SV
2
47MC
Torpedo Control
SV
2
48 MC
Stores conveyor (obsolescent)
NV
1
49MC
Unassigned
50MC
Integrated operational
intelligence center
SV
2
27.123.0
228
Chapter 11 AMPLIFIED VOICE SYSTEMS
Table 11-1. Shipboard Announcing Systems continued
Circuit
System
Importance
Readiness Class
51MC
Aircraft Maintenance and
handling control
SV
2
52MC
Unassigned
53MC
Ship Administrative
NV
4
54MC
Repair Officer's Control
NV
4
55MC
Sonar Service
NV
4
56MC
Unassigned
57MC
Unassigned
58MC
Hanger Deck Damage Control
V
1
59MC
SAMID Alert
SV
3
Legend:
* = Central amplifier systems
V = Vital
SV = Semivital
NV = Nonvital
27.123.0
r 1
ALARM
CONTACT
MAKERS
CONTROL AMPLIFIER
EQUIPMENT" I
CIRCUIT IMC
MICROPHONE
CONTROL
STATIONS
CIRCUIT IMC S
LOUDSPEAKER
CIRCUIT IMC 86MCI
i MICROPHONE
I CONTROL
| STATION i
I 1
' GROUPS
CIRCUIT 6MC 1
LOUDSPEAKER
GROUP I
(BULL HORN) j
. VISUAL ALARM '
I INDICATORS \
J
POWER FROM
MAIN 1C
SWBD
>MUTING AND PRIORITY
SIGNALS TO
SHIP'S ENTERTAINMENT
AND OTHER ANNOUNCING
EQUIPMENT
Figure 11-1. Typical 1MC-6MC systems installation.
229
140.125
SHIPBOARD ELECTRICAL SYSTEMS
7.19
Figure 11-2. IMC - 6MC microphone control
station.
diagram of a typical 1MC-6MC systems instal-
lation found aboard a destroyer. Power for oper-
ating the system is obtained from the 120-V
60-Hz distribution section of the main 1C switch-
board.
ALARMS AND ALARM CONTACT MAKERS. ~~
A number of different alarms may be generated
within and broadcast over circuit IMC. The
nature and number of alarms is dependent to
some extent on the mission of the ship aboard
which the system is installed. As a rule, how-
ever, all IMC systems installed aboard surface
ships are capable of generating and broadcasting
collision alarms, chemical attack alarms, and
general alarms. The alarms are generated by
oscillators located within the control/ amplifier
equipment. Alarms are activated by closing a
lever-operated switch type contact maker (de-
scribed in chapters). Each alarm that is generated
and broadcast by the system has at least one
of its own contact makers, i.e., the general
alarm is actuated by a general alarm contact
maker, the collision alarm is actuated by a
collision alarm contact maker, etc. The alarm
contact makers are installed at various locations
such as the bridge and quarterdecks where they
are easily accessible to watchstanders.
The alarms are broadcast over circuit IMC
only and they have priority over IMC voice
transmissions. Additionally, a system of prior-
ities is part of the alarms. The order of alarm
priorities is (1) collision alarm, (2) chemical
attack alarm and (3) general alarm, If a low
priority alarm is being sounded and the contact
maker for a higher priority alarm is closed,
the lower priority alarm will be silenced and the
higher priority alarm will be transmitted over
the IMC loudspeakers. Conversely, the closure
of a low priority alarm contact maker has no
effect on a high priority alarm that is being
sounded.
MICROPHONE CONTROL STATIONS.
Microphone control stations (fig. 11-2) provide the
facilities to make voice announcements over the
IMC or 6MC system and to select the loud-
speakers over which the voice announcements
will be broadcast. The microphone control station
consists of a microphone with a press-to-talk
switch, loudspeaker group selector switches,
busy lamps, and a signal level meter.
To make a voice transmission from a micro-
phone control station, first, depress the loud-
speaker group selector switches (crew, officer,
engineers, etc.) over which you desire to make
the transmission. Next, depress the press-to-
talk switch and speak into the microphone with
sufficient force to cause the deflections of the
signal level meter pointer to peak at midscale.
The busy lamps indicate that a transmission
is in progress from another microphone control
station.
Ships usually have at least two microphone
control stations. The bridge is equipped with a
1MC-6MC microphone control station and the
quarterdeck is equipped with a IMC only micro-
phone control station, which does not have an
intership loudspeaker (6MC) selector switch.
The microphone control stations are also under
a system of priorities as are the alarms. Bridge
IMC transmissions have priority over the quar-
terdeck IMC transmissions. Under certain con-
ditions, which will be discussed later in this
chapter, the IMC has priority over the 6MC.
LOUDSPEAKERS AND LOUDSPEAKER
GROUPS. Loudspeakers convert the amplified
voice and alarm electrical signals to sound.
Several different types of loudspeakers are used
in 1MC-6MC systems to suit different needs.
Figure 11-3 illustrates two loudspeaker types.
230
Chapter 11 AMPLIFIED VOICE SYSTEMS
HOUSING
HORNS
ROTATABLE
BASE
DOUBLE-FOLD HORN
LOUDSPEAKER
MULTIUNIT STRAIGHT-HORN
LOUDSPEAKER
Figure 11-3. Dynamic horn loudspeakers.
7.17
The double-fold horn is used with circuit IMC
in weather decks or in high noise areas. The
nultiunit straight-horn (bullhorn) is a high-power
init used for intership (6MC) voice commani-
lations.
For purposes of selectivity and damage iso-
ation, the various IMC loudspeakers are organ-
zed into groups and subgroups. A typical
lestroyer installation consists of four loud-
speaker groups (1) officers, (2) topside, (3)
jrew, and (4) engineers. A IMC voice trans-
nission may be made via any one or all of the
speakers by selecting the appropriate speaker
froup or groups at the microphone control station.
Jince the loudspeakers of the groups are separated
nto physical zones, i.e., officers' country, engi-
leering spaces, etc., a damaged loudspeaker in
i group could result in the complete loss of IMC
ransmission to an entire area of the ship.
To overcome this handicap, groups are divided
nto subgroups with an action cutout switching
irrangemsnt. The subgroups consist of several
oudspeakers from the parent group. Loud-
jpeakers of the subgroup are selected so that
lot all of the speakers of a space or geographical
Lrea belong to a specific subgroup. A damaged
oudspeaker of a IMC system subgroup may be
isolated through the action cutout switching ar-
rangement without completely losing IMC capa-
bility to a major space or area.
Usually one or two 6MC loudspeaker units are
installed. The 6MC loudspeakers are not divided
into groups. The desired 6MC loudspeaker is
selected at the bridge microphone control station.
VISUAL ALARM INDICATORS. Visual alarm
indicators consist of lighting fixtures with red
lamps installed in machinery spaces where high
noise levels are common. The red lamp lights
steady when the collision and chemical attack
alarms are sounded and flashes when the general
alarm is sounded.
CONTROL/AMPLIFIER EQUIPMENT. The
control amplifier equipment is the heart of the
1MC/6MC system. All signals and control func-
tions that are required for system operation are
either processed by or developed within it.
Control/amplifier equipment:
1. Generates alarm signals of various charac-
teristics when activated by the closure of an
alarm contact maker.
231
SHIPBOARD ELECTRICAL SYSTEMS
2. Amplifies voice and alarm signals to a
magnitude sufficient to drive the many loud-
speakers of the system,
3. Channels the amplified voice signals to
the specific loudspeaker groups as selected at
the microphone control station.
4. Channels the ordered alarm signals to all
the loudspeaker groups of the system.,
5. Provides a backup amplifier and oscillator.
AMPLIFIER-OSCILLATOR
ASSEMBLY
6. Provides facilities to control the volume of
voice signals and to monitor, test, and isolate
certain components of the system.
7. Performs specific functions in accordance
with a fruilt-in set of priorities.
8. Energizes the visual alarm indicators when
an alarm is sounded.
The two units of the control/ amplifier equip-
ment such as the one illustrated in figure 11-4
contain the oscillators, preamplifiers, power
POWER AMPLIFIER ASSEMBLY
Figure 11-4. AN/SIA-114 control/amplifier equipment.
232
140.36
Chapter 11 AMPLIFIED VOICE SYSTEMS
Table 11-2. Alarm Signal Characteristics
Signal
Characteristic
Collision Alarm
Chemical Alarm
General Alarm
Unassigned Alarm "A"
Unassigned Alarm "B"
Flight Crash Alarm
Triple pulsed 1000 Hertz tone
Continuous 1000 Hertz tone
Gong tone
500-1500 Hertz jump tone (1 1/2 per sec)
600-1500 Hertz jump tone (6 per sec)
Simulated siren tone
amplifiers, and control devices necessary for
the system to perform as stated above.
Oscillators. The oscillators provide the
various alarm signals required for the system.
The sound characteristics of each alarm are
different so that each may be easily distinguished
from the others. The sound characteristics for
each alarm have been standardized (table 11-2)
on surface craft so that the alarm signals on
all ships are identical. Only three alarms
collision, chemical attack, and general have
been mentioned thus far. These three alarm
signals may Tbe sufficient for some ships, whereas
for other ships additional alarm signals may be
required. So that the control/amplifier equipment
may be installed on several classes of ships,
the oscillators of most equipment are capable
of producing other designated alarm signals, such
as the flight crash alarm. They are also capable
of producing signals that are not designated by
name, but are reserved for future use. The
oscillators of the equipment shown in figure 11-4
produce two such alarm signals the unas signed
alarm "A" and the unassigned alarm "B."
These two alarm signals have their own individual
sound characteristics and are reserved for future
use as may be directed by higher authority.
The control/amplifier equipment has two
oscillator subassemblies which are contained
within the amplifier-oscillator assembly. Only
one of the two oscillators is required to produce
the alarm signals required of the system. A
rotary selector switch located on the front panel
)f the amplifier-oscillator assembly is used to
select which oscillator will produce the system
alarm signals a The inactive oscillator is then
available for maintenance- or repair, or to produce
signals that may be used to test an inactive pre-
amplifier and power amplifier.
Preamplifier and Power Amplifier. The
preamplifier is contained within the amplifier
oscillator assembly. It amplifies the weak voice
signals from the microphones and the alarm
signals from the oscillators to a value sufficient
to drive the power amplifier. To compensate for
the different voice levels of system users, the
preamplifier contains special circuits which at-
tenuate those high level input signals that would
cause overdriving and distortion at the loud-
speakers.
The power amplifier is contained in the
power amplifier assembly and receives the
relatively weak voice signals and alarm sig-
nals from the preamplifiers and greatly in-
creases their power level to a level that is
sufficient to drive the loudspeakers. The sig-
nals from the power amplifier are returned to
the amplifier-oscillator assembly for distribution
to the different speaker groups.
One preamplifier in conjunction with one
power amplifier form one channel. Usually,
there are two preamplifiers and two power
amplifiers in the 1MC-6MC system connected
to form two channels (channel A and channel
B), The equipment shown in figure 11-4 contains
two amplifier channels each of which is capable
of producing 500 watts of audio power.
The two identical amplifier channels are
provided to permit independent operation of
the IMC and 6MC systems if desired, one system
on each of the two channels. A channel selector
switch is provided on the front panel of the
233
SHIPBOARD ELECTRICAL SYSTEMS
amplifier-oscillator assembly to provide flexi-
bility to the system. The selector switch can
be positioned for systems operation as follows:
1. IMC on channel A, 6MC on channel B
2. IMC and BMC on channel A
3. IMC and 6MC on channel B
The last two combinations may be used to
isolate one of the channels for service. The
first position listed is used for independent
operation of the IMC and 6MC.
Because a large amount of heat is radiated
from the power amplifiers, many ships operate
with both systems on the same channel, with the
remaining channel secured and in reserve. This
mode of operation greatly reduces the radiated
heat and resulting insulation deterioration. As
the 6MC system is used seldom, as compared
to the IMC system, operating in this manner
presents few operational disadvantages. However,
it does extend equipment life.
As previously discussed, under certain cir-
cumstances the IMC voice transmissions have
priority over 6MC voice transmissions. When the
system is operating with the IMC on amplifier
channel A and the 6MC on amplifier channel
B, it is possible to broadcast over the 6MC
system from the bridge microphone station and,
at the same time, to broadcast over the IMC
from the quarterdeck microphone station. When
both systems are operated on the same amplifier
channel, IMC transmission takes priority over
6MC transmissions.
1MC-6MC Announcing
Systems Operation
The 1MC-6MC system, as stated previously,
provides a means of transmitting IMC alarms,
IMC voice, and 6MC voice. Listed below are basic
descriptions of how the systems perform these
tasks. The descriptions are general in nature and
vary depending on the particular equipment and
installation.
IMC ALARM TRANSMISSIONS. Transmis-
sion of a IMC alarm begins when an alarm
contact maker collision, chemical attack, or
general is closed. Closure of the contact maker
energizes a specific relay for that alarm, setting
in motion a sequence of events within the control/
amplifier equipment which disables the circuitry
for other alarms having lower priority and com-
pletes the circuits that cause a nurnber of other
relays to operate to:
1. Energize the on-service oscillator in such
a manner as to cause it to produce the desired
sound.
2. Establish priority over 1MC-6MC voice
transmissions.
3. Illuminate the busy 1 and busy 2 (IMC
busy and 6MC busy) lamps at the microphone
control stations to alert personnel that IMC
and 6MC voice transmissions are not possible.
4. Provide a control signal to ship's enter-
tainment and other announcing equipment to
mute or disable it.
5. Connect the output of the selected oscillator
to the input of the amplifier channel selected
for IMC transmissions.
6. Apply power to the selected amplifier
channel.
7. Operate all the loudspeaker group relays
so that the alarm signal will be transmitted over
all of them.
8. Energize the visual alarm indicators -
steady for collision and chemical attack alarm,
intermittent for general alarm.
For the collision and chemical attack alarms,
the above conditions will continue to exist only
as long as the contact maker is closed. Momentary
operation of the general alarm contact maker
causes the alarm to sound for a predetermined
15-second period.
IMC VOICE TRANSMISSIONS. Operation of
the microphone press-to-talk switch at the micro-
phone control station sets up the following se-
quence within the control/ amplifier equipment,
1. Connects the microphone output to the
input of the amplifier channel selected for IMC
transmissions.
2. Causes the loudspeaker group relays to
energize for those loudspeaker groups that have
been selected at the microphone control station,
This action connects the output of the amplifier
channel to those loudspeaker groups over which
it is desired to transmit the voice information,
3. Energizes the busy lamps on the micro-
phone control stations as follows:
a. IMC on channel A and 6MC on channel
B: the busy 1 (IMC busy) lamp is illuminated
at all microphone control stations.
b. 1 MC and 6MC on channel A or IMC
and 6MC on channel B: both the busy 1 and busy
234
Chapter 11 AMPLIFIED VOICE SYSTEMS
2 (IMC and 6MC busy lamps) are illuminated
at all microphone control stations.
4. Establishes IMC priority over the 6MC
transmission if both the IMC and SMC systems are
sharing the same amplifier channel.
5. Sends control signal to the ship's enter-
tainment to mute its transmission.
6. Applies power to the amplifier channel
selected for IMC service.
7. The operator makes his transmission
through the microphone, regulating the force
of his voice, to cause the pointer of the meter
on the microphone control station to peak at
mtdscale deflection.
6MC VOICE TRANSMISSIONS. 6MC voice
transmissions are very similar to IMC voice
transmissions. 6MC transmissions differ mainly
in that:
1. They can only be made from the bridge
>r other specifically designated 1MC-6MC
nicrophone control stations.
2. The 6MC loudspeaker is selected as op-
>osed to the IMC loudspeaker groups.
3. The busy lamps on the microphone control
stations are energized as follows:
a. IMC on channel A and 6MC on channel
3: the busy 2 (6MC busy) lamp is illuminated
.t all microphone control stations.
b. IMC and 6MC on channel A or IMC
.nd 6MC on channel B: both busy lamps are
Lluminated at all microphone control stations.
laintenance and Safety
Maintenance personnel must be very careful
r hen servicing this equipment. All the common
ales of safety and good sense apply, as they
r ould to any other electrical equipment. Special
are should be exercised with this equipment,
owever, because:
1. Voltages in excess of 1,000 volts maybe
resent within the control/amplifier equipment.
2. The sound pressure level emitted from a
MEG loudspeaker (bullhorn) is very high. Trans-
tission should not be made over the 6MC
/stem while personnel are in the vicinity of the
mdspeaker.
JTERCOMMUNICATING
iTSTEMS
An intercommunicating (intercom) system
msists of a number of permanently located
stations. Each station contains all the necessary
components to provide two-way amplified voice
communication, supplemented by signal lamps,
between two stations. The units used in intercom
systems serve the same purposes and operate
basically the same as the commercial intercom
units so common in many business offices.
Navy and commercial intercom units differ mainly
in their physical appearance. The typical intercom
systems used aboard naval ships consist of a
number of compatible intercom units and their
interconnecting cabling.
Intercom Unit
There are several basic types of intercom
units in use throughout the Navy, with certain
variations to the basic types. These types differ
mainly in physical appearance and in the materials
used in their construction. Irrespective of their
appearance and construction, their electrical
characteristics have been standardized to permit
intercom units of different manufacturers and
construction to be used in one common system,,
Figure 11-5 illustrates two intercom units.
The units are made by different manufacturers
but they are compatible, and each is capable
of originating calls to as many as 10 other
intercom units. There are similar units which
can call 20 other stations, and there is another
type which can originate calls to only two other
stations.
SHIP'S ENTERTAINMENT
SYSTEMS
A separate shipboard announcing system,
circuit SE, is used primarily for the entertain-
ment of ship's company and is capable of broad-
casting commercial radio programs, prerecorded
information, and voice announcements of an
educational or entertainment nature to various
locations within the ship.
SHIP'S ENTERTAINMENT
EQUIPMENT
There are several different types of ship's
entertainment equipment which is specifically
manufactured for installation aboard naval ships.
In addition, many ships have ship's entertainment
systems which are composed in part or entirely
of equipment designed for commercial use.
235
SHIPBOARD ELECTRICAL SYSTEMS
7.25:140.127
Figure 11-5. Intercom units.
Figure 11-6 is a diagram of a typical ship's
entertainment system. This system consists of
various input equipment, a control/ amplifier
console, power amplifier assembly, and as many
loudspeakers as required.
Input Equipment
The input equipment consists of those devices
that supply the desired entertainment or educa-
tional programs to the ship's entertainment sys-
tem. The actual composition of input equipment
may vary, depending on the particular installation.
A typical selection of input equipment is illus-
trated in figure 11-6. An additional phonograph,
tape player, radio, etc. may be connected to the
auxiliary input jack if desired.
Control/ Amplifier Console
The control/ amplifier console pictured in
figure 11-6 is used in many shipboard installa-
tions. The console together with the power
amplifier assembly contains the necessary con-
trol devices and amplifiers to accept from
any two of the available inputs and to retransmit
that information over two independent channels
to the various loudspeakers. The console also
contains a tape recorder that may be used as an
input for one of the entertainment channels,
or it may be used to record information for
later use. As previously discussed in this chapter,
control signals from the 1MC-6MC system actuate
devices within the console which mute or silence
ship's entertainment transmissions.
Loudspeakers
Ship's entertainment speakers are installed in
berthing, messing, and recreation spaces. Each
speaker unit is provided with a channel selector
switch and volume control to permit the individual
to select and regulate the volume of the channel
he desires to hear. The loudspeakers of the
ship's entertainment system are arranged in
groups as they were in the 1MC-6MC system*
Isolation switches (located on the control/
amplifier console) permit individual speaker
groups to be disconnected from the remainder
of the system if desired.
Commercial Ship's
Entertainment Equipment
The entertainment systems aboard many ships
are composed in part or entirely of commercial
236
Chapter 11 AMPLIFIED VOICE SYSTEMS
INPUT
EQUIPMENT
CONTROL/AMPLIFIER
CONSOLE
LOUDSPEAKERS
SELECTED
CHANNEL 182
INFORMATION FROM CONTROL/
AMPLIFIER CONSOLE TO
POWER AMPLIFIER ASSEMBLY
CHANNELS 182
CHANNELS 1S2
CHANNELS 18 2
CHANNELS 182
CHANNEL 1 8 2
t INFORMATION FROM POWER
AMPLIFIER ASSEMBLY TO
CONTROL AMPLIFIER
CONSOLE FOR DISTRIBUTION
TO LOUDSPEAKERS
POWER AMPLIFIER ASSEMBLY
27.340
Figure 11-6. -Basic diagram of ship's entertainment equipment.
237
SHIPBOARD ELECTRICAL SYSTEMS
equipment* This commercial equipment usually
is more compact, less expensive, and more
attractive than Navy equipment, but it presents
certain disadvantages that should be considered
prior to its purchase and installation. Some
disadvantages are;
1, Safety commercial equipment is not al-
ways electrically safe for shipboard use.
2, Construction- commercial equipment is
not always rugged enough to withstand the rigors
of shipboard use.
3, Supply support commercial equipment is
not supported by the Navy Supply System* In
many instances it will be very difficult to obtain
repair parts for commercial equipment*
SHIP'S ENTERTAINMENT
SYSTEM OPERATION
A properly maintained and operated ship's
entertainment system contributes greatly toward
a happier ship's company, A poorly maintained
and incorrectly operated ship's entertainment
system is worse than having no system at all.
It should be remembered that, at many times,
the entertainment system is often the only source
of world news and one of the few sources of
entertainment for the ship's company. It should
also be remembered that no two person's opinion
of what constitutes entertainment agrees com-
pletely, and it is impossible to please everyone
all the time.
The entertainment system should present a
wide variety of programs. If possible, pro-
gramming should be done by several persons
of varied interests. Many times it will be possible
to enlist the services of crew members in
scheduling programs for the system.
SOUND MOTION PICTURE
SYSTEMS
Sound motion picture systems are designed
for training, briefing, and entertaining. The
equipment used is similar to commercial motion
picture projection equipment which projects
16-mm sound film for viewing. The types of
equipment used and the size of installation vary
with each ship. Usually ships are equipped with
at least two 16-mm sound motion picture pro-
jectors and several installed or portable loud-
speakers.
SOUND MOTION
PICTURE FILM
The sound motion picture film Is one of the
most expensive components of a sound motion
picture projection system? it is also the most
susceptible to damage.
Film Construction
Sound motion picture film used by the Navy
is identical to that used by the civilian population.
It is composed of a nonflammable cellulose
acetate base upon which is bonded the emulsion.
The base supports and acts as the transporter
or vehicle for the emulsion. The emulsion is
the component in which the image, including
the sound track, is recorded by the photographic
process. Figure 11-7 is an exploded view of
motion picture film. The edge of the film is
perforated by sprocket holes, which are used
to aid in transporting the film through the movie
projector mechanisms. The opposite edge of the
film contains the photographic record of the
sound recording, the sound track. As shown
in figure 11-7 the image appears inverted to the
observer. The projection process causes the
image to once again appear right side up on the
movie screen.
Film Care
The care of motion picture films is largely
a matter of common sense. Navy motion picture
films should receive the same care as one
would expect to give his own films. Store them
in a cool, dry place and handle them carefully.
Most film damage is a result of improper
care, defective projection equipment, or improper
stowage. The most common types of film damage
are liquid damage, scratches, and tearing.
DAMAGE FROM LIQUIDS, Most liquids (in-
cluding water) will damage the emulsion surface
of films. Exposure to liquids causes the emulsion
to become discolored; figures and colors run
together. The most common cause of this form
of film damage are improper stowage and the
careless coffee drinker.
SCRATCHES. The emulsion of the film is
a relatively soft material, and it is easily
scratched. Scratched films appear to have vertical
lines or bars across them and the reproduced
sound portion of the film is distorted. Improper
handling, defective projection equipment and poor
238
Chapter 11 AMPLIFIED VOICE SYSTEMS
SOUND TRACK
PICTURE FRAME
SPROCKET HOLE [UD
PICTURE UPSIDE
DOWN
7,66(77C)
Figure 11-7. Section of 16-mm film,
projector operators cause most scratched film
damage. To avoid this form of damages
1. Exercise care to keep the film and pro-
jection equipment as clean as possible.
2. Keep the projection equipment properly
adjusted.
3. Ensure that projection equipment operators
are properly trained.
TORN OR BROKEN FILM e Gross mishand-
ling by projection equipment operators or de-
fective equipment results in broken or torn
film. This type of damage can be prevented by
properly maintaining your projection equipment
and properly training its operators.
Film Management
Generally, motion picture film available to
shipboard personnel may be categorized as being
either educational or entertaining in nature.
The policies for use, management, and distri-
bution of each type is different. Entertainment
films are under the cognizance of the Navy
Motion Picture Service, while the policies con-
cerning educational films are established by
the Chief of Naval Education and Training. To
ensure the efficient utilization of each type of
film, several reports and forms must be main-
tained by shipboard personnel. The records
required for educational films are different
from those required for entertainment film.
ENTERTAINMENT F I L M. Entertainment
film for shipboard viewing is available through
your local Navy Motion Picture Exchange (MPX).
The rules governing the operation of local MPX's
and the use of their films by shipboard personnel
are contained in the Navy Motion Picture Service
Manual. This manual covers all aspects of enter-
tainment film usage and handling and gives
information on the use of forms, reports and
records that are part of the system. The manual
also specifies that all movie projector operators
are to be adequately trained and designated in
writing by the commanding officer. Failure to
comply with the regulations contained within
the manual could result in the suspension of
your command's entertainment film privileges.
For purposes of familiarization, some of
the records and forms associated with enter-
tainment films are listed below. You should
consult the Navy Motion Picture Service Manual
for specific instructions concerning these records
and forms.
Inspection and Exhibition Booklet. Each en-
tertainment film print has its own Inspection
and Exhibition Booklet (I & E Booklet) which
remains with the film as long as it is in service.
The I & E Booklet serves several functions.
The first pages contain a brief description of
what the film is about and lists the major stars
that appear in it. The remaining pages (fig. 11-8)
are a record of where and when the film has
been exhibited and its condition before and after
each exhibition. This information aids the MPX
in determining who may be responsible for any
damage to the film and it also helps in determining
that a film has been used sufficiently to warrant
its removal from circulation. Entries on the
record pages shoyild be brief, legible, and specific.
They should be made in ink, and each entry mast
be signed by the designated movie officer. These
entries are checked by MPX personnel when
the film Js returned.
239
SHIPBOARD ELECTRICAL SYSTEMS
SHIP OR STATION
DATE OF
EXHIBITION
CONDITION BEFORE
EXHIBITION
CONDITION AFTER
EXHIBITION
SIGNATURE
COMMISSIONED OFFICER
S.S.
G-oocL
G
U.S.
8-3-73-
GOoD C.Q M$ i T"/ o /J
GoocL
g,9.s
3-1-73
Good
Figure 11-8. Inspection and Exhibition Booklet Record pages.
27.394
PROGRAM NO.
MOTION PICTURE PRINT INVENTORY CARD
NAVPERS 3045 (REV 1971)
INSTRUCTIONS: (REPORT SYMBOL BuPers 1710-6)
TO THE SHIP OR STATION HAVING CUSTODY OF THIS PRINT
1. DETACH THIS CARD ON THE LAST DAY OF THE ABOVE MONTH.
PRINT NO.
MONTH
YEAR
2. ENTER U-I-C CODE AND ADDRESS IN THE SPACES PROVIDED BELOW.
3. IF THIS PRINT IS RECEIVED WITH A CARD(S) FOR A PREVIOUS
MONTH(S), DETACH AND SUBMIT CARD(S) IMMEDIATELY.
4. THIS. IS A MONTHLY PRINT INVENTORY CARD
AIRMAIL TO:
NAVY SPECIAL SERVICES ADMINISTRATIVE ACTIVITY
NAVY MOTION PICTURE SERVICE
311 FLUSHING AVENUE
BROOKLYN, NEW YORK 11205
PROGRAM! PRINT
14 1'5 16 17 18 19
DO NOT BEND OR FOLD
SENDERS CORRECT MAILING ADDRESS INCLUD NS ZIP CODE
U I. C.
27.395
Figure 11-9. -Motion Picture Inventory Card.
Motion Picture Print Inventory cards (fig.
11-9) are attached inside the rear cover of the
I & E Booklet and provide information for the
Navy Motion Picture Service to periodically
account for each film and its general location.
Use of the cards is self-explanatory.
Motion Picture Inspection Record. Motion
picture exchanges generally require shipboard
personnel to complete a record of inspection
prior to the receipt of a print. Figure 11-10
is a checkoff list which serves as a guide to
the representative from your command and aids
240
Chapter 11 AMPLIFIED VOICE SYSTEMS
INSTRUCTIONS
a. For preparation by movie operator prior to exhibiting of each
MOTION PICTURE INSPECTION RECORD jw*-* **//*.,*
NAVPERS 3043 (Rev. 4-61) *' *" "" by NMPX ' S in making ro ""' ae ia *"' ions '
PROGRAM NUMBER
PROGRAM CONDITION CODE
GENERAL PRINT
CONDITION
SPECIFIC DEFECTS NOTED
E EXCELLENT
G GOOD
U USABLE
NU NON-USABLE
B BRITTLE HS HEAVY SCRATCH SPL LIGHT SPROCKET DAMAGE
C CRIMPS M MISSING SPH HEAVY SPROCKET DAMAGE
LS LIGHT SCRATCH N NICKS W WATERMARKS
FEATURE f-f -~
OC/<^ AMOA/Y/Mnts^
NO. REELS
3
SHORT SUBJECTS
#2
#3
TOTAL REELS Jg
INSPECTION FACTORS SHORT SUBJEaS
REELS OF FEATURE
(Vie above code) # }
#2 #3 12
3
4 S &
PROTECTIVE LEADER
G, M
G
SYNCHRONIZING LEADER
G M
G
TITLE AND CAST
L5 G
3
PICTURE
Gi uy
G
SOUND TRACK
L5 G
G
ALONGSIDE SOUND TRACK
Cji C^
q
SPROCKET HOLES
{* p) / ^
Q
SPLICES
C G
G
ENDING
G
/Wi
GENERAL PRINT CONDITION
(Use Code abort) ^
REMARKS
DISPOSITION
NMr-
>X USE
VAULT
A/MF*K a<&-
DATE
/7 3
'ULY 76
SIGNATURE (Inspector)
SIGNATURE OF MOTION PICTURE OFFICER PRIOR TO EXHIBITION
Figure 11-10. Motion Picture Inspection Record.
241
77.269
SHIPBOARD ELECTRICAL SYSTEMS
him in his inspection. Performing an inspection
at the Motion Picture Exchange and noting the
condition of the film will prevent your ship's
being held responsible for previous damage.
Activity, Damage, Loss and Destruction
Report. Upon the discovery of loss, damage,
or destruction of a print, the Motion Picture
Exchange will initiate and forward an Activity,
Damage, Loss and Destruction Report (fig. 11-11)
to the command that last had custody of the
damaged or lost print. The form is divided
into two parts. The top half is filled out by the
investigating MPX. The activity from which the
information is requested completes the lower
portion and returns the form to the requesting
MPX. The MPX will attempt to affix the blame
for the damaged print by the information received.
Exhibition, Transfer and Inventory Record,
The Exhibition, Transfer and Inventory Record
is a monthly record of each film received by a
ship. All films received by your command are
recorded on this form. This form (fig. 11-12)
lists the name of the print, from whom it was
received, its condition after exhibition, and to
whom it was transferred. The form also lists
those personnel from your activity who were
designated as projectionists. A new form must
be prepared each month* It must be signed by the
commanding officer or his designated repre-
sentative (movie officer). The completed Motion
Picture Exhibition, Transfer and Inventory
Record forms should be retained aboard.
Notification of Motion Picture Transfer.
When ships are underway for extended periods
or when they are in ports not serviced by an
MPX, motion pictures may be transferred di-
rectly from one ship to another. When such
exchanges are made, the Notification of Motion
Picture Transfer Form (fig. 11-13) must be
completed. This form, when filled out and signed
by a representative of the receiving command,
is a receipt for films transferred from your
command.
Transfers are NOT to be made directly
between ships in a port served by an MPX.
Films are NOT to be informally loaned to other
commands. Remember that your activity will
be held responsible for any damage or loss that
occurs to a film while it is officially in your
custody.
Request for 16-mm Motion Picture Sea
Prints. Generally, film prints issued for use
by ships while they are in port may NOT be
taken to sea. Film prints that are to be taken
to sea must be specifically requested on a
Request for 16 mm Motion Picture Sea Prints
Form (fig. 11-14). Instructions for completion
and submission are listed on the form.
TRAINING FILMS, In comparison to enter-
tainment films the record keeping chores con-
cerned with Navy training films are minor.
Films which are of general interest to shipboard
personnel are available from the Naval Education
and Training Support facilities in San Diego
and Norfolk. They may be obtained through
official correspondence with these support facil-
ities. Loss or damage to training films should
be reported to the applicable support facility.
A complete listing of available training films is
contained in the United States Navy Film Catalog,
NAVAIR 10-1-777.
SOUND MOTION PICTURE
PROJECTION EQUIPMENT
The principles of operation of Navy pro-
jection equipment are identical to those of com-
mercially available equipment. The 16-mm Singer
Graflex Movie Projector (fig. 11-15) is a slightly
modified version of commercially available
equipment. This projector, however, unlike its
civilian counterparts, has been tested and is
considered safe for shipboard use. The fact that
it is considered safe for shipboard use does
not mean that it will remain so indefinitely.
It means that insofar as could be determined
by the testing program, when used in a reasonable
manner, the projector is as safe as it is tech-
nically and economically feasible to make it.
NOTE: MOVIE PROJECTORS, LIKE ALL
PORTABLE ELECTRICAL EQUIPMENT
ABOARD SHIP, ARE POTENTIAL SHOCK
HAZARDS AND SHOULD BE TREATED AS SUCH*
A movie projector's portability makes it
susceptible to physical damage which could make
it unsafe for use. Its portability means that it
is not physically bonded to the ship's hull;
physical damage could cause dangerous voltages
to be present on its outer surfaces. These
voltages await a person's contact which will
cause current to flow through his body to the
ship's hull.
242
Chapter 11 AMPLIFIED VOICE SYSTEMS
TRUCT.ON REPORT
.. 6 April 197-
From: Of f i cer-l n-charge , Navy Motion Picture Exchange. NORFOLK, VA.
MPE - 100
To:
Commanding Officer
U.S.S. UNDERWAY (AD- 12)
c/o Fleet Post Office
New York, N.Y.
Subj : PROGRAM .
2250
A2
FEATURE TITLE CROOKS ANONYMOUS (STD) B&W
SHORT SUBJECTS PENNY PALS (STD) E
1. Subject film was recently exhibited at your activity. It ia requested that information be furnished
concerning:
[j Damage of film Q] Loss of film
2. After completing the items below forward this form an indicated.
/s/ A.J. JONES, LT., USN
(Signature)
From- U S S UNDERWAY (AD-12)
185 10 April 197-
!IAL DATE
(activity name)
To: Officer-in-charge, Navy Motion Picture Service, Naval Station, 136 Flushing Ave., Brooklyn I, N.Y. 11251
1. As requested above
the following report
is submitted:
1 April 197-
NUMBER OF SHOWINGS ON BOARD
TWO
Is operato
E
r an MPO school
YES [""I NO
graduate?
[X] YES
n NO
during
projection and after
EYES
showing?
a NO
prepared?
E
YES [I]
NO
Motion Picture Inspection Record (Navpers 3043) for program 2250 - A2 indicates that
subject program was in GOOD condition before and after each of the two exhibitions on
board.
/s/ R.J. COX, LCDR, USN
Figure 11- 11, Activity Damage, Loss and Destruction Report.
243
77.270
SHIPBOARD ELECTRICAL SYSTEMS
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244
Chapter 11 AMPLIFIED VOICE SYSTEMS
NOTIFICATION OF MOTION PICTURE TRANSFER
HAMPERS 1710/1 (11-66)
(Formerly HAVPE8S 3042)
Navy Motion Picture Service, Naval Station, 136 Flushing Ave.. Brooklyn. N. Y. 11251
Officer in Charge , Navy Motion Picture Exchange, Naval Station, Pearl Harbor, Hawaii
CERTIFIED NO. TCMD NO. SIGNATURE
INSURED NO. A NO,
PROGRAM AND
PRINT NUMBER
NUMBER
OF REELS
PRODUCTION TITLE
* TCK 0N001414112P013-XX
2606-P15
3
THE WHISPERERS
2607-P15
2608-P15
2609-P15
3
1
3
3
OUR MAN FLINT
SPOTLIGHT ON TASMINIA, TELE SPORTS #723
ACT ONE
THE MAN FROM NOWHERE
NO ENTRY BELOW THIS LINE
1 BDLE - 71 LBS. -1.6 CtJFT.
PLEASE RECEIPT COPY & RETURN
DATE RECEIVED SIGNATURE
4/10/71 la/ 1. M. CASSADY, CDR, USN
INSTRUCTIONS
Forward original and a copy to the receiving activity via Air Mail. One copy shall accompany shipment and one copy shall be
ailed to the Navy Motion Picture Service, U.S. Naval Station, 130 Flushing Avenue, Brooklyn, New York 11251. Originator shall
ter all necessary shipping information in the spaces provided at the tup of this form. Listing for each film program shall include the
g fo
tle o
m prog
complete program number with print designator, number of reels in program and feature title of program. Each listing is understood
to be one case unless otherwise indicated. Receiver shall acknowledge receipt by entering date of receipt and signature in the spaces
p
li
.
rovided at the boitom of this form and promptly return a copy to the originator. Receiver shall also clear!/ indicate any programs
isted above but not received.
77.268
Figure 11-13. Notification of Motion Picture Transfer.
245
SHIPBOARD ELECTRICAL SYSTEMS
REQUEST FOR 16 MM MOTION PICTUR
FLTGEN Form 1710/1 (Rev. 12/66) 0199 217 1
REF: COMSERVLANTINST 1700.4 ser
1. All requests will be filled out in fill
E SEA PRINTS
013
m F^. \ct76
(Date)
ies /OT Com Sefv Pac
1. (Information classified CONFIDENTIAL, is to be included and the
request classified CONFIDENTIAL. Information classified higher than CONFIDENTIAL is to be omitted and
the statement "CLASSIFIED HIGHER THAN CONFIDENTIAL " inserted in the appropriate blanks.)
2. Request for 14 sea prints or less are to be submitted directly to the Officer-in-Charge of the NMPX where
prints will be drawn.
3. Requests for 15 or more sea prints shall be submitted in original and two copies, to COMSERVLANT with a
copy to the NMPX where prints are to be drawn. Requests should be submitted at least 14 days prior to the date
required, whenever possible.
4. Sea prints are to be drawn from the NMPX nearest the port of departure unless a draw from another NMPX is
specifically authorized by COMSERVLANT.
5. Atlantic NMPX's are located in ARGENTIA, BOSTON, BROOKLYN, CHARLESTON, GUANTANAMO,
KEY WEST, LONDON, MAYPORT, NAPLES, NEW LONDON, NEWPORT, NORFOLK, PHILADELPHIA,
RODMAN, SAN JUAN, and aboard deployed FBM Submarine Tenders (To be used primarly asSSBN exchanges).
From: Commanding Officer, ^J^ ^
^ to / -
^, rsfcfcl4STORH V t
))
To:
(Nome of Ship/Activit
y)
NO. PRINTS REQUESTED NO. PERSONNEL PORT OF DEPARTURE
23 378 NORfoix, V/A
ETD (TIME AND DATE*
0^00 ^ MlW 1*176
NO. SHIPS IN COMPANY ISSUING NMPX
14MPX. NORfCtK, VA.
PICK-UP DATE
T HAP, l\T6
NEXT PORT SERVICED BY NMPX
BoOHAW, PfefsJAtM*
ETA (TIME AND DATE) SI
GNATURE ( (CO OR DESIGNATED AUTHORITY)
A.V. STRAND IcR
CAPt, U.S.M.
COPY TO:
FOR NMPX USE ONLY
DATE NO. OF SEA PRINTS ISSUED AF
PROVED BY:
C^ Hu PftO
REMARKS:
1
Figure 11-14. Request for 16-mm Motion Picture Sea Prints,
246
27.396
Chapter 11 AMPLIFIED VOICE SYSTEMS
Figure 11-15. 16-mm Singer
projector.
27.397
Graflex movie
Projector Maintenance,
Uare, and Safety
Improperly maintained movie projectors have
)een the cause of several electrical shock fatali-
les and many injuries. Ensure that only approved
uid properly maintained motion picture equip-
nent is used aboard your ship. Strictly adhere
;o 3-M Maintenance requirements and proce-
lures.
A properly indoctrinated operator is, Tby far,
he greatest asset in properly maintaining movie
projectors and film*
The routine projector cleaning performed by
he operator, prior and subsequent to each film
ihowing, is extremely vital to the longevity
>f equipment and film. Dirt within the projector
jollects on surfaces that come in contact with
he film. This dirt, if allowed to accumulate,
*esults in scratched film. Dirt also finds its
yay into the projector's mechanisms and ac-
selerates their deterioration. When badly worn
irojector components cannot maintain alignment
vith respect to each other, the resulting mls-
ilignment causes improper projector operation
.nd torn or broken film.
Improper handling of the film and projector
>y the operator is another cause of damage to
oth film and projectors. A large amount of
damage results from mishandled film and pro-
jector or incorrectly operated projection equip-
ment.
The results of improperly trained projector
operators have been listed above. However, the
most important reason for training projector
operators is for personal safety.
A properly trained operator is more aware
of what could be a hazard to him or others
and of what actions he should take when he
detects a hazard.
Movie Projector
Operator Training
Only those personnel who have been properly
trained and designated as qualified operators of
projection equipment may operate movie pro-
jectors aboard ship. Training and qualification
are essential because of the potentials for elec-
trical hazard and film damage associated with
the equipment. A programmed instruction
consisting of two volumes (16-mm Projector Op-
erator, NAVEDTRA 5053-1&2, stock Nos. 0502-
LP-025-2650 and 0502-LP-025-2660, Volumes
1&2 respectively) is available for training movie
projector operators aboard ship. Completion
of the programmed instruction and on-the-job
training should provide sufficient knowledge for
the trainee to meet the qualification standards
as set forth in the Navy Motion Picture Service
Manual and applicable on-board standards.
INTERIOR VOICE
COMMUNICATIONS SYSTEM
In earlier sections of this manual a variety
of the conventional voice communications systems
were covered. They may be classified as belonging
to one of four basic groups:
1. Sound-Powered Telephone Systems
2. Dial Telephone Systems
3. Intercommunication Systems (Intercom)
4. Central Amplifier Announcing Systems
These systems were originally designed in the
1930's and 1940's to fulfill a specific communi-
cations need. Each group has its own character-
istics and each is better suited to support a
particular shipboard evolution than are the other
three.
The systems which are members of these
groups are reliable and as a rule provide adequate
247
SHIPBOARD ELECTRICAL SYSTEMS
interior communications capabilities, tout have
two major disadvantages.
The first disadvantage is that each is designed
to operate individually without provisions to
interface with systems that possess different
communications capabilities. Such systems re-
quire that if a user is to have access to the
capabilities of all four communication groups,
he must have devices that provide him access
to each group (i.e., a dial telephone, a IMC
microphone control station, an intercommuni-
cations unit, a sound-powered telephone, etc.).
The second disadvantage is that individual
wiring must be installed to a location for each
system that the users are to have access to.
Thus, as the communications needs of a location
change, wiring changes must be made to add or
delete the systems required.
The Interior Voice Communications System
(IVCS) is an integrated communications system
that attempts to solve the shortcomings of older
systems. IVCS combines the features of sound-
powered telephones, dial telephones, and inter-
communications units into one system and it
can interface with other shipboard communi-
cations systems. Additionally, IVCS provides
features and services not available from any
of the conventional shipboard communications
systems.
IVCS
The IVCS, as installed on the new Landing
Helicopter Assault (LHA) ships, is a computer-
controlled circuit- switching voice communica-
tions system. The IVCS consists of terminals
(user access devices), accessories, and two
computer- controlled Interior Communications
Switching Centers (ICSC). Two ICSC's are used
to provide redundancy and are so located that
simultaneous damage to both is unlikely.
Terminal Devices
Two types of terminal devices (network
terminal and dial terminal) are used with the
IVCS. The type of terminal, the way it is
connected into the system, and the computer
program determine the type of service that is
provided to each user.
NETWORK TERMINAL. The network termi-
nal (fig. 11-16) provides service comparable
to that provided by sound-powered telephone
systems. By depressing one of the four numbered
pushbuttons, the user will be connected to any
one of four networks. The networks are hard-
wired circuits with a predetermined number of
network terminals connected to them. The net-
works are connected in a manner that is similar
to sound-powered telephone string circuits. Each
network circuit is also connected to one of the
Interior Communications Switching Centers. The
nature of this connection will be covered later
when the IVCS organization is discussed. The
network circuits are manned for certain ship-
board evolutions, as sound-powered circuits
would be on a ship equipped with conventional
1C systems.
DIAL TERMINAL. The dial terminal pro-
vides service that can be most easily compared
to that provided by a dial telephone system,
The dial telephone terminals (fig. 11-17) are
connected to the Interior Communications Switch-
ing Centers (ICSC). They are used in a manner
that is comparable to a commercial dial telephone
with pushbutton dialing.
TERMINAL AC C E SSORIE S. There are
several types of accessories designed for use
with the dial and network terminals. These
accessories include headsets, handsets, spray-
tight enclosures which permit the installation
of the terminals in exposed areas, and loud-
speaker units.
The loudspeaker units (fig. 11-18) are designed
for use with either the dial or the network termi-
nals. Both the units illustrated in figure 11-18
are equipped with press-to-talk switches. Addi-
tionally, by depressing the hands free pushswitch
on the unit pictured infigure 11-18B, the operator
can communicate without using the press-to-talk
switch. Both these accessories permit terminal
users to communicate without either a handset
or headset, providing user service that is com-
parable to that provided by commercial speaker
phone units.
Interior Communications
Switching Center (ICSC)
The ICSC's are the heart of the IVCS. They
perform the switching actions necessary to con-
nect the calling party to the called party. In
this manner the ICSC's are similar to the auto-
matic switchboards of a dial telephone system*
However, most similarity ends at this point
because the design, construction, and wiring of
the automatic telephone switchboard dictates
the manner in which it will perform; changes
to its performance can only be made by changing
248
Chapter 11 AMPLIFIED VOICE SYSTEMS
27,398X
Figure 11-16. Network terminal,,
its physical characteristics. The switching
mechanisms of the ICSC's, on the other hand,
are controlled by a computer and its associated
memory. The switching devices of the ICSC
perform their operations in a prescribed manner
because the computer instructs them to do so,
not because it is physically impossible for them
to perform in any other way. As an example:
in dial telephone systems certain telephones
may cut into the conversations of others or
have other special features as a result of equip-
ment modifications. In the IVCS special features
are granted to a terminal on the basis of the
information stored in the computer memory. If
a terminal requires the capability of cutting in
on the conversations of others, instructions
are placed into the computer memory which
permit it to do so.
249
SHIPBOARD ELECTRICAL SYSTEMS
27.398X
Figure 11-17. -Dial terminal.
IVCS ORGANIZATION
Figure 11-19 is a block diagram of the IVCS.
As illustrated, the IVCS contains two ICSC's
each of which operates independently of the other.
Each ICSC receives 440 VAC power from the
ship's distribution system. In addition, each
ICSC is provided with standby battery supplies
capable of supplying power to each ICSC for
1 hour in the event ship's power is lost. The
ICSC's are connected together by the trunk and
net intertie lines which permit the terminals
connected to one ICSC to communicate with
the terminals connected to the other ICSC. The
Emergency Throwover Operation (ETO) lines
also connect the two ICSC's together.
The ETO lines are part of a feature that
allows an ICSC to provide service to a limited
number of dial terminals normally assigned
to the other ICSC. If the ICSC to which they
250
Chapter 11 AMPLIFIED VOICE SYSTEMS
A. STANDARD LOUDSPEAKEfMJNIT
HANDS FREE -INDICATOR LAMP
HANDS FREE
PUSHSWITCH
Figure 11-18. Loudspeaker units.
27.399
SHIPBOARD ELECTRICAL SYSTEMS
i
CO
O
252
Chapter 11 AMPLIFIED VOICE SYSTEMS
are normally assigned fails, predesignated dial
terminal^ are served Tby the other ICSC through
the ETO lines.
Approximately half of the dial and networks
terminal devices of the IVCS are connected
to each ICSC.
The dial terminals of the IVCS are connected
to the ICSC's in such a way that the dial commands
originated by them may be processed by the
computer. The computer then causes the switch-
ing mechanisms to connect the calling party to
the called party, unless it is restricted from
doing so by the instructions contained within its
memory.
The network terminals of the IVCS are not
connected to the switching mechanisms of the
ICSC's in the same manner as the dial terminals.
Network terminals cannot originate calls to
other terminals or networks. They are, as stated
before, connected to each other to form a network
circuit that is similar to sound-powered telephone
string circuits. Under normal circumstances
network terminals can communicate with only
those other terminals connected to the same
network circuit. However, the network circuits
are connected to the ICSC's in such a way that
it is possible for certain dial terminals (desig-
nated in the computer memory) to connect them-
selves through the switching mechanisms to the
network circuits.
Interfaces
As shown in figure 11-9, the dial terminals
connected to each ICSC can interface with the
following ship's systems or equipment:
1. Ship's radio communications equipment
2. Ship's central amplifier announcing sys-
;ems (IMC, 2MC, SMC, etc.)
3. Sdund-powered telephone circuits (Bridge
;o Bridge, weapons, etc.)
4. The manual telephone switchboard, which
.s part of the IVCS, is comparable to the
attendant's cabinet of a dial telephone system
serves two functions:
a. Inport: It permits the IVCS to interface
vith up to eight shore telephone lines.
b. At sea: It permits the IVCS to interface
vith eight multichannel radio links that are used
irimarily for amphibious operations by embarked
Xlarines.
5. Several short-range, two-way radios that
,re specifically designated as the base stations
or the Man-on-the-Move (MOM) Communications
System. This is a special two-way radio com-
munications system that consists of individual
personal radio transceivers which provide, as
the name implies, man-on-the-move communi-
cation capabilities. The MOM transceivers are
operated on one of the several radio frequencies
designated specifically for them. By interfacing
with the base stations, the IVCS make sit possible
for a dial terminal user to be connected to one
of the MOM radio networks and to communicate
with personnel equipped with MOM transceivers.
6. Although not actually an interface, the
dial terminals may gain access to the network
terminals of the IVCS through the switching
mechanisms of the ICSC's.
Not every dial terminal can gain access to
the above listed systems or equipment. For
instance, before a dial terminal can interface
with the IMC, specific instructions must be
contained within the memory of the computer
which permits that individual terminal to inter-
face with the IMC, In this way only those dial
terminals that are specifically authorized may
interface with any equipment or system*
The ability to interface with other systems,
as can be imagined, provides the IVCS user with
communications capabilities that far exceed those
of conventional interior communications systems.
From one dial terminal it is possible to talk
to someone in the next compartment or, through
the ship's radio equipment it is possible to
talk to someone on the other side of the world.
Special Features
The IVCS provides many special features,
some of which are provided by conventional 1C
systems, but many of which are unique to the
IVCS. These special features are listed below.
DUAL TONE MULTIFREQUENCY (DTMF)
DIALING, The IVCS dial terminals utilize Dual
Tone Multifrequency (DTMF) Dialing, which is
comparable to the pushbutton dialing used by
most commercial telephone companies.
Normally, the IVCS terminals utilize four digit
DTMF dialing.
HUNT-THE-NOT-BUSY. The hunt-the-not-
busy feature is not new, having been used in many
dial telephone systems. However, the manner
in which this feature is provided by the IVCS
is new. In dial telephone systems, the attendant's
cabinet is usually provided with the hunt-the-
not-busy feature. For the attendant's cabinet
253
SHIPBOARD ELECTRICAL SYSTEMS
to receive this service, wiring changes are
made to a group of sequential numbers (usually
237, 238, 239, 230). Having been modified, it
is possible for a party to dial the first sequential
number (237) and, if that number is already
in use, the switching mechanisms of the auto-
matic switchboard steps to the next higher idle
sequential number (238, 239, 230). A busy signal
is received by the calling station only if all
the numbers in the group are busy.
The automatic telephone system, because of
equipment design, must use sequential numbers
to provide the hunt-the-not-busy feature. The
IVCS uses a stored program in memory and,
therefore, any number can be programmed to
belong to a hunt-the-not-busy group. For example,
7142, 5237, and 7413 can be in a hunt-the-not-
busy group. These numbers can easily be changed,
simply by changing that portion of the memory
that pertains to them.
CONFERENCE CALL. -The conference call
feature permits a dial terminal, which is author-
ized in the system memory, to dial up to five
other terminal numbers at the same time and
set up a conference call. All six parties can
then converse with one another.
COMMAND NET. The command net feature
permits a dial terminal, which is authorized
in the system memory, to dial a special four-
digit code. Dialing of this special code causes up
to 30 predesignated (in memory) terminals to
be rung at the same time. As the called terminals
are answered, they join the command net and
all parties can converse with each other.
PRIVACY OVERRIDE. The privacy over-
ride feature permits a dial terminal, which is
authorized in the system memory, to complete
a call whether or not the called terminal is
busy.
If a called terminal is busy, the override
(OV) pushbutton is depressed on the dial terminal
(fig. 11-17), and the number is redialed to permit
the calling terminal to join the busy parties.
A 1-second tone is generated and placed on the
busy circuit to alert the persons on the busy
circuit that someone has joined their conversa-
tion.
RING OVERRIDE. All dial terminals that do
not have the privacy override feature will auto-
matically have the ring override feature.
If the called terminal is busy, the override
(OV) pushbutton is depressed and the number
is redialed. Three short tones are placed on
the audio lines of the busy parties. These tones
alert the busy terminals that someone is trying
to call one of them. The busy terminals should
then complete their conversation as quickly as
possible and hang up to allow the other party
to call.
CALL FORWARDING. Call forwarding per-
mits the user of a dial terminal, which is
authorized in the system memory, to have his
incoming calls forwarded to another terminal.
For instance, the captain might be expecting an
important call, but an appointment requires his
presence in the wardroom. By dialing a special
code the captain can instruct the computer to
direct all his incoming calls to the wardroom.
After these instructions are placed into the
system, anyone dialing the captain's terminal
will cause the wardroom terminal to ring. Upon
returning to his cabin, the captain dials another
code and cancels his call -forwarding instructions.
ABBREVIATED ADDRESSING. Abbreviated
addressing permits authorized dial terminals
to call certain other terminals by depressing
the (A) pushbutton (fig. 11-17) and one numerical
pushbutton. The dial terminal that is to use
abbreviated addressing designates up to 10 fre-
quently called terminals in the system memory.
By depressing the abbreviated address push-
buttons, the calling terminal is connected to the
called terminal. This feature, in conjunction
with a loudspeaker accessory, provides user
service that is similar to that provided by con-
ventional intercom units.
IVCS SUMMARY
As you can see from the previous discussion,
the IVCS offers many features and services not
provided by the conventional interior communi-
cations systems. The system described herein
is presently planned for installation in LHA's
only. Although these ships represent only a small
part of the overall ships' population, more of
these systems, or similar systems, will be
installed in future ship types.
254
CHAPTER 12
GYROCOMPASSES
Gyrocompasses are devices which use the
principle of a gyroscope to obtain an indication
of true north. Gyrocompass systems develop
own ship's heading and transmit information
to various navigation and weapons stations and
to other equipment throughout the ship. Gyro-
compasses are identified by the mark-mod sys-
tem. The mark (Mk) number designates a major
development of a compass. The modification
(Mod) number indicates a change to the major
development.
Gyrocompasses depend on the physical prop-
erties of the spinning gyroscope and the effects
of the earth* s gravity and rotation for their
operation. In this chapter we shall discuss:
(1) The basic gyroscopic principles as they
apply to a functional gyrocompass system.
(2) The basic operating principles of the
Mk 23 and Mk 19 gyrocompasses.
(3) Gyrocompass records and logs.
You will find additional information in current
editions of Synchro, Servo and Gyro Fundamentals,
NAVEDTRA 10105; 1C Electrician 3&2, NAVEIP
TRA 10558; 1C Electrician l&C. NAVEDTRA
10557; and the manufacturer's manual for your
specific installation.
THE GYROSCOPE
The gyroscope is a heavy wheel, or rotor,
suspended so that its axle is free to turn in
any direction. The rotor axle is supported in
a ring by two bearings at S and S f , as illus-
trated in figure 12-1. This ring is supported
inside a slightly larger outer ring by studs
and bearings at H and H f . The outer ring is
mounted in the supporting frame by studs and
"bearings at V and V f . The inner and outer
rings are called gimbals. The supporting frame
VERTICAL(TURN)- ' ** V
AXIS
HORIZONTAL (TILT)
AXIS
Figure 12-1. The gyroscope.
77.194
is not a part of the gyroscope but merely
supports it. The rotor and the two gimbals are
balanced about their axes. The axes are mutually
perpendicular and intersect at the rotor's center
of gravity. The bearings of the rotor at points
S and S ! and the gimbals at points V, V f , H,
and H 1 are considered to be completely free of
friction. Actually, there is always some friction,
but it has been reduced to such an extent that
it is considered nonexistent.
255
SHIPBOARD ELECTRICAL SYSTEMS
THREE DEGREES
OF FREEDOM
The gyroscope rotor has three degrees of
freedom freedom to spin, freedom to turn, and
freedom to tilt which permit the rotor to
assume any position within the supporting frame
(fig. 12-1). The rotor is free to spin about
its own axle (spinning axis S-S') the first
degree of freedom. The inner gimbal ring is
free to tilt on its bearings about the horizontal
axis (H-H T ) the second degree of freedom.
The outer gimbal ring is free to turn on its
bearings about the vertical axis (V-V f ) the
third degree of freedom.
GYROSCOPIC
PROPERTIES
When a gyroscope rotor is spinning rapidly, the
gyroscope develops two properties rigidity of
plane and precession which it does not have
when the rotor is at rest. Rigidity of plane and
precession together with the earth's gravity
and rotation make it possible to convert a gyro-
scope into a gyrocompass.
Rigidity of Plane
When the rotor of a gyroscope is set spinning
with its axle pointed in one direction (fig. 12-
2A), the rotor continues to spin with its spin
axle pointing in the same direction, no matter
how the supporting frame of the gyroscope is
tilted or turned (fig. 12-2B). As long as the
gimbal bearings are frictionless and the rotor
spins, no amount of turning of the supporting
frame can change the plane of the rotor with
respect to space. This property of the gyro-
scope is known as rigidity of plane, gyroscopic
inertia, rigidity in space, or stability. It can
be explained by Newton's first law of motion
which states that a body in motion will continue
to move at a constant speed in a straight line
unless acted upon by an outside force. The
rigidity of the gyroscope may be increased by
(1) making the rotor heavier, (2) by causing the
rotor to spin faster, or (3) by concentrating most
of the rotor weight near its circumference. If
two rotors with cross sections like those shown
in figure 12-3 are of equal weight and rotate
at the same speed, the rotor in figure 12-3A
27.128(77A)
Figure 12-2. Rigidity of plane of spinning
gyroscope.
will be less rigid than the rotor in figure
12-3B. This condition exists because the weight
of the rotor in figure 12-3B is concentrated
near the circumference. Gyroscopes and gyro-
compass rotors are both constructed with most
of their weight concentrated near the circum-
ference.
256
Chapter 12 GYROCOMPASSES
(A)
77.196
igure 12-3. Weight distribution in rotors.
^cession
As previously stated, because of rigidity of
ne, movements of the supporting frame have
effect on the direction in which the spin
e of a spinning gyroscope points. To change
the direction in which the axle points, you must
apply a force to the gyroscope rotor about its
spin axis. A downward force on one end of the
rotor axle attempts to tilt the gyroscope about
the horizontal axis and, if the rotor is not
spinning, the axle will tilt in response to the
force. However, if the rotor is spinning, as in
figure 12-4A, its rigidity will resist any attempt
to tilt the rotor about the horizontal axis and,
instead, the gyroscope will precess about the
vertical axis. Any force (F) attempting to turn
the spinning gyroscope about the vertical axis
is similarly resisted and results in precession
(P) about the horizontal axis (fig. 12-4B).
Any force that tends to change the plane of
rotation causes a gyroscope to precess. Pre-
cession continues as long as there is a com-
ponent of force acting to change the plane of
rotation, and precession ceases immediately
when the force is removed.
If the plane in which the force acts moves
at the same rate and in the same direction as
the precession which it causes, the precession
will be continuous. This is illustrated by figure
12-5 in which a weight W representing an un-
balanced condition about the horizontal axis is
'--HORIZONTAL-
AXIS
PRECESSION
ABOUT THE VERTICAL
AXIS
A
PRECESSION ABOUT THE
HORIZONTAL AXIS
B
27.131
Figure 12-4. Precession.
257
SHIPBOARD ELECTRICAL SYSTEMS
i S'
77.197
Figure 12-5. Continuous precession.
suspended from the end of the spin axle Al-
though the weight is exerting a downward force,
it must be remembered that the force itproduces
against the particles in the spinning wheel is
horizontal. This force is imparted to the par-
ticles in the wheel as exemplified by arrows
F and F T . If the wheel rotates clockwise as
seen from the weighted end, precession will
occur in the direction of arrow P. As the
gyroscope precesses, it carries the weight around
with it so that forces F and F ? continuously act
at right angles to the plane of rotation, and pre-
cession continues indefinitely.
A simple way to determine the direction of
precession is illustrated in figure 12-6. Con-
sider the force that tends to change the plane
of rotation of the rotor as it is applied to
point A at the top of the wheel. This point does
not move in the direction of the applied force,
but a point displaced 90 in the direction of
rotation moves in the direction of the applied
force. This is the direction of precession.
Forces of Translation
Whereas, forces which attempt to turn and
tilt a gyroscope cause precession, forces which
act in a straight line through the center of
gravity of a gyroscope will not cause precession
and are known as forces of translation. Forces
which produce precession may be classified
as twisting forces or torques which act about
either the vertical or horizontal, or both the
vertical and horizontal axes. Forces of translation
do not impart a twisting force or torque about
any axes, but, to repeat, they act in a straight
line through the center of gravity of the gyro-
scope. Referring back to figure 12-1, you can see
that the gyroscope is suspended by gimbal rings
in such a way that the spin, vertical, and hori-
zontal axes bisect at a point that also coincides
with the gyroscope 's center of gravity. Any force
acting in a straight line along one of these axes or
any force acting simultaneously along two or all
three of the axes is a force of translation and
LJ _,.__.
27.131(77A)
Figure 12-6. Direction of precession.
258
Chapter 12 GYROCOMPASSES
will not cause precession. Thus the base and
gimbaling system of the gyroscope provide it with
not only the three freedoms but also permit the
gyro to be moved as a unit in any direction
without causing precession.
EFFECT OF EARTH'S
ROTATION
As explained previously, a spinning gyroscope
can be moved in any direction without altering
the angle of its plane of rotation. If the base of
a free-spinning gyroscope were placed on the
earth's surface at the equator with the spinning
axis of the gyroscope horizontal and aligned
east and west, an observer in space above the
north pole (fig. 12-7) would note that the earth
rotates counterclockwise from west to east and
carries the gyroscope along. As the earth rotates,
rigidity of plane keeps the gyroscope's spin axle
pointed in the same direction at all times.
Assume that the gyroscope is set spinning at
0000 hours with its spinning axis aligned east
and west and parallel to the earth's surface. At
0600, 6 hours after the gyroscope was started,
the earth has rotated 90 but the axle of the
gyroscope is still aligned as before. At 1200
the earth has rotated 180 while the gyroscope
retains its original alignment. At 1800 the earth
has rotated 270 while the gyroscope still retains
its original alignment. At 0000 the earth has
rotated 360, the gyroscope has returned to
its original starting position, and throughout
the 24-hour period the alignment of the spin
axle of the rotor has remained constant.
The effects of rigidity of plane described
above appear quite differently to an observer
standing on the earth's surface. As the earth
rotates, the observer moves with it, and the
gyroscope wheel appears to rotate about its
horizontal axis. Figure 12-8 shows how this
spinning gyroscope is placed on the earth's
surface at the equator at 0000 hours with the
darkened end of the spinning axis horizontal and
pointing toward the observer. At 0600, 6 hours
after the gyroscope was started, the earth has
rotated 90 and the gyroscope axle apparently
has tilted. To the observer, the darkened end
of the axle points straight up and is vertical
to the earth's surface. At 1200 the darkened
end of the gyroscope axle is horizontal again,
but it now points away from the observer.
At 1800 the darkened end of the gyroscope
axle is again vertical and points straight down.
At 0000 the earth has rotated 360 and the
gyroscope appears to the observer to be back
in its original position while, in fact, it has
been fixed in space for the entire period.
The rotation of the gyroscope axle as seen
by the observer on the earth's surface is known
12.144(77A)A
Figure 12-7. Free gyroscope at the equator
viewed from space above the north pole.
12.144(77A)B
Figure 12-8. Spinning gyroscope at the equator
viewed from the earth's surface.
259
SHIPBOARD ELECTRICAL SYSTEMS
as apparent rotation. Apparent rotation is caused
by rigidity of plane which maintains the plane
of the gyroscope wheel parallel to its original
position in space. The apparent rotation that
makes a gyro appear to tilt albout the hori-
zontal axis is referred to as horizontal earth
rate (H.E.R.) effect. This effect varies with
the cosine of the latitude and is maximum at
the equator and zero at the poles.
Now assume that the spinning gyroscope,
with its spinning axis horizontal, is moved to
the north pole (fig. 12-9). To an observer in
space above the north pole, the gyroscope axle
remains fixed and the earth rotates under it.
To an observer on the earth's surface, the
gyroscope appears to rotate about its vertical
axis. This apparent rotation about the vertical
axis is referred to as vertical earth rate (V.E.R.)
effect, and it varies with the sine of the latitude.
It is maximum at the poles and zero at the
equator.
When the spin axis of the gyroscope is
aligned so that it is parallel to the earth's
spin axis, apparent rotation will take place
around the gyroscope's spin axis and it cannot
be readily observed.
When placed at any point between the equator
and either pole, a gyroscope whose spinning axis
is not parallel to the earth's spinning axis
has an apparent rotation that is a combination
of horizontal earth rate and vertical earth rate.
The combined earth rate effects at this point
make the gyroscope appear to rotate partly
about the horizontal axis and partly about the
vertical axis. The H.E.R. causes the gyro to
appear to tilt about its horizontal axis and the
V.E.R. causes the gyroscope to appear to turn
about its vertical axis. The magnitude of the
apparent turn or tilt is dependent on the latitude
where the gyroscope is located. At latitudes
near the equator, the gyro appears to tilt more
than turn. At latitudes near either pole the gyro
appears to turn more than tilt. This apparent
rotation is illustrated in figure 12-10 by a
spinning gyroscope with its spin axis pointed
north and parallel to the earth's surface at
45 N latitude. To an observer on the earth's
surface, the gyroscope appears to both turn
and tilt.
To summarize, a gyroscope, if set on any
part of the earth 1 s surface with its spinning
axis not parallel to the earth's spin axis will
appear to rotate. The H.E.R,, which is maxi-
mum at the equator and zero at the poles,
causes the gyroscope to appear to tilt about its
APPARENT ROTATION
VERTICAL
AXIS
EARTHS
ROTATION
77.198
Figure 12-9. A gyroscope with its spin axis set
horizontal at the north pole; observed from a
point in space beyond the equator.
77.199(140B)
Figure 12-10. Apparent rotation of a gyroscope
at 45N latitude.
260
Chapter 12 GYROCOMPASSES
horizontal axis. The V.E.R., which is zero at
the equator and maximum at the poles, causes
the gyroscope to appear to turn about its vertical
axis. At any latitude between (equator) and
90N or 90S (north or south poles), the apparent
rotation of the gyroscope will take place about
the horizontal and vertical axes simultaneously.
MAKING THE GYROSCOPE
INTO A GYROCOMPASS
We have discussed the properties of the simple
gyroscope and the effects of the earth's rotation
upon it. Now, let us investigate the manner in
which rigidity of plane and precession plus the
effects of horizontal earth rate and gravity
may be used to make a simple gyroscope align
its spin axis north- south and maintain that align-
ment.
Before the simple gyroscope is converted
into a gyrocompass, its base and gimbaling
rings (as shown in fig. 12-1) will be changed
as shown in figure 12-11 A. The simple gyro-
scope is modified by replacing the inner gimbal
with a sphere or case, a feature of all gyro-
compasses which serves to protect the rotor.
Also, the base has been replaced by a phantom
ring, or phantom. The phantom differs from
the base of a simple gyroscope in that the base
of the simple gyroscope is stationary, whereas,
the phantom of the modified gyroscope is driven
Tby a servomechanism (not shown) so that it is
maintained in alignment with the spin axis of
the gyroscope. The servomechanism that drives
the phantom also positions the compass card and
the synchro transmitters which provide indi-
cations of own ship's heading (OSH). Look again
at figure 12-11 A. The gyrosphere of the modi-
fied gyroscope provides the rotor with the free-
dom to spin. The vertical ring provides the
gyrosphere with the freedom to turn; the vertical
ring is suspended from the phantom so that it
is free to tilt, and the phantom is maintained
in alignment with the spin axis of the gyro-
scope by a servomechanism. Further, to become
a gyrocompass the gyro must be modified so
that it can:
1. Align its axis on the north- south plane
(meridian)
2. Align its axis nearly horizontal
3. Maintain its alignment horizontally and on
the meridian, once attained.
SEEKING THE
MERIDIAN
The first step in making the modified gyro-
scope into a gyrocompass is to make the gyro
seek the meridian. To do this, a weight W
is added to the bottom of the vertical ring as
shown in figure 12-11B. This weight causes
the previously balanced gyro rotor/vertical ring
assembly to become unbalanced about its hori-
zontal axis, being heavier at the bottom than at
the top. The modified gyroscope and weight
are placed at the equator with the gyroscope
VERTICAL
RING
GYRO ROTOR
GYROSPHERE
PHANTOM
VERTICAL
RING
GYRO ROTOR
GYROSPHERE
PHANTOM
27.135:136
Figure 12-11. A. Modified gyroscope. B. Modified gyroscope with weight.
261
SHIPBOARD ELECTRICAL SYSTEMS
spin axis horizontal, pointing east-west, and
the rotor spinning clockwise as viewed from
the west (point A, fig. 12-12A and 12-12B).
As the earth rotates, the east end of the gyro-
scope spin axis rises in relation to the earth's
surface (point B, fig. 12-1 2A and 12-12B). This
action is the result of rigidity of plane, which
causes the gyroscope to point in the same
direction, and H.E.R., which causes the gyro to
appear to tilt about its horizontal axis in relation
to the earth's surface. As the gyro and vertical
ring appear to tilt, the weight W rises against
the pull of gravity. The earth's gravity acts
against the weight and causes a torque to be
applied about the horizontal axis of the gyro-
scope. This torque causes the gyroscope to
precess about its vertical axis in the direction
indicated at point C in figures 12-12A and
12-12B; the gyroscope spin axis then has moved
and the spin axis is no longer aligned east-west.
VERTICAL
RING
GYRO ROTOR
ASSUME EXTERNAL MEANS
ARE PROVIDED TO TURN
PHANTOM SO AS TO FOLLOW
THE GYRO IN AZIMUTH.
Figure 12-12. Effect of weight and earth's rotation on the gyroscope.
262
27.137
Chapter 12 GYROCOMPASSES
As the end of the gyroscope which was first
pointing east (which will now Tbe referred to as
the north end) continues to rise due to the H.E.R.,
the torque on the gyro caused by the weight
Tbecomes greater since the moment arm through
which the weight acts gets longer due to the
greater tilt. As the speed of precession is
directly related to the torque, the gyroscope
turns about its vertical axis as shown at point
D, figures 12-12A and 12-12B at an increasing
speed until the axis is on the meridian (aligned
north- south as shown at point E of figures
12-12A and 12-12B.
At point E of figures 12-12A and 12-12B,
the gyroscope is aligned north- south, but the
tilt, the torque caused by the tilt and the weight
W, and the speed of precession are all at
maximum; therefore, the gyroscope continues to
precess past the meridian. As the north end of the
gyroscope's spin axis crosses the meridian, the
H.E.R. acts upon it and causes the tilt to start
decreasing. As the tilt decreases, the rate of
precession decreases. Finally, as a result of
the H.E.R. the axle becomes horizontal and,
since the weight on the vertical ring no longer
produces a torque, precession stops. At this
point (point F of figure 12-12B), the north
axle has precessed as far west of the meridian
as it was originally to the east of the meridian
(point A of fig. 12B).
As the earth continues to rotate, the north
end of the gyroscope spin axis starts to fall.
The weight is raised against the forces of gravity
on the opposite side of the gyroscope's hori-
zontal axis, causing the gyroscope to precess
back toward the meridian. When the gyroscope
reaches the meridian (point G of fig. 12-12B),
its north axle is tilted downward to a maximum
degree and the torque from the weight cause it
to precess past the meridian. As the north
axle once again processes to the east of the
meridian, the H.E.R. starts to reduce the tilt.
Finally, the gyroscope precesses back to its
original starting point (point A of fig, 12-12B),
while the H.E.R. has caused the north axle
to be once again level with the earth's surface.
At this point the gyroscope's north axle has
completed one complete cycle, but H.E.R. con-
tinues to affect the gyro and causes its north
axle to once again start to rise, and the weight
causes the gyro to precess from east back toward
the meridian (north). This cycle will repeat
itself indefinitely with the gyroscope oscillating
back and forth across the meridian from east
to west and back again to the east.
By hanging a weight on the vertical ring of the
gyroscope, the first requirement for making a
gyroscope into a gyrocompass making the gyro
axle seek the meridian has been fulfilled. How-
ever, some means must be provided to suppress
the oscillations so the gyro wheel will quickly
come to rest with its axle level in the north-south
position.
SETTLING ON
THE MERIDIAN
To suppress the oscillations of the gyro
about the meridian a small weight is added
to the sphere in which the gyro is housed. This
weight (Wi) is placed on the east side of the
gyrosphere in the position shown in figure 12-13.
With the gyro spin axis level, the force produced
by gravity acting upon weight W^ and the gyro-
scope's vertical axis are perpendicular to the
earth's surface and parallel to each other;
therefore, no torque is exerted about the gyro-
scope's vertical axis by W 1% However, when the
gyro tilts, due to H.E.R , the vertical axis of the
gyroscope is no longer perpendicular to the
earth's surface, and the force of gravity acting
on Wi imparts a torque about the vertical axis
of the gyroscope. The torque about the gyro-
scope's vertical axis causes the gyroscope to
precess about its horizontal axis. The net result
of Wi is to cause the gyroscope to precess about
VERTICAL
RING
GYRO ROTOR
WEIGHT W,
GYROSPHERE
WEIGHT
W
PHANTOM
27.138
Figure 12-13. Gyroscope with weights on the
vertical ring and sphere.
263
SHIPBOARD ELECTRICAL SYSTEMS
its horizontal axis in a direction that opposes
the tilt caused by the effects of H E.R.
Now, when placed on the equator aligned
east-west, as a result of the leveling action of
weight Wi, the gyro axle is not tilted upward
as much when it reaches the meridian as it
was with only weight W. Since the gyro axle
is not tilted as much, the torque produced by
weight W is not so great. Therefore, the gyro
axle will not precess as far to the west of the
meridian as it was east of the meridian when it
was started.
After reaching the point where the axle is
level and as far west of the meridian as it is
going due to the action of weights W and Wj,
the H.E.R. is still causing the axle to tilt
downward. As a result, the forces due to the
weights are reversed, and torques are created
which precess the gyro to the east and upward.
The same action takes place in the reverse
direction. The gyro is not precessed as far to
the east as it was to the west. Thus, the added
weight Wj causes the ellipse to be reduced
each successive oscillation; the north end of the
gyro axle will follow a spiral path as shown in
figure 12-14 instead of the previous elliptical
path.
A careful observation of the action of the two
weights makes it apparent that the only position
of rest that the gyro can find is with the gyro
axle horizontal and on the meridian. In other
words, the free gyroscope has been converted
into a true north-indicating gyrocompass.
An instrument such as the one we have
described will indicate true north accurately as
long as it is located at the equator and is not
transported over the surface of the earth. When
this compass is relocated to a latitude other than
the equator, the V.E.R., which was zero at the
equator, will then affect the gyro and cause it
to turn away from the meridian. When the
gyrocompass is transported across the surface
GYRO COMPASS SETTLING
27.139
Figure 12-14. Effect of weights W and W^ on the gyroscope.
264
Chapter 12 GYROCOMPASSES
of the earth, accelerations on the weights will
cause torques on the gyro and precess it away
from the meridian.
Many other outside forces affect the gyro-
compass causing it to indicate directions (gyro
errors) other than true north. The different
types of gyrocompasses employed by the Navy
compensate for or eliminate gyro errors in
different ways. Some of the forces which pro-
duce errors may not affect a particular type
of gyrocompass because the design of the com-
pass negates the forces which produce certain
errors. The other errors that cannot be elimi-
nated are compensated for in different ways
in different compass systems.
In the older mechanical compasses the errors
that cannot be eliminated* through design or
adjustment, are corrected by precalculating the
error for a given set of conditions and, then,
simply by shifting the lubber's line that amount
necessary to correct the error. In other words,
the spin axis of the older mechanical compass
is very seldom exactly aligned on the meridian
(true north), but rather is pointed to some
location a few degrees either east or west
of the meridian. Mechanical devices on the
compass are used to crank in corrections to the
compass for the forces that are causing the
errors. The mechanical devices then shift the
lubber's line (correct the compass) so that
the compass indicates as though the spin axis
were truly aligned on the meridian.
The electrical compasses take an entirely
different approach to produce an accurate indi-
cation of true north.
The electrical gyrocompass uses an electronic
control system to make it seek and indicate
true north, vice the weights used on the simple
gyrocompass. The force of gravity combined
with the tilt of the gyro rotor as a consequence
of H.E.R. are used as the controlling factors,
as they were with the simple gyrocompass.
However, instead of being used directly to con-
trol the compass, the force of gravity acts on
a special device that generates an electrical
signal that is proportional to the tilt of the
gyro rotor. The signal from the device is ampli-
fied and used to apply torques electrically about
the horizontal and vertical axes of the gyro-
compass, and to cause the gyro's spin axis to
settle on the meridian and level.
Devices within the electrical compass develop
an electrical signal that produces a torque
on the gyrosphere which is equal and opposite
to those factors that would cause errors. In
this way, the gyrosphere of the electrical com-
pass is maintained level and on the meridian
continuously.
The Mk 19 and Mk 23 are the electrical
gyrocompasses which are rapidly replacing the
mechanical compasses. They comprise the
majority of the gyrocompass systems employed
on Navy ships. In the next section of this chapter
we shall discuss briefly the Mk 23 and Mk 19
gyrocompass systems, their principles of
operation, capabilities, and nomenclature.
MK 23 GYROCOMPASS
The Mk 23 gyrocompass is a small electrical
compass capable of withstanding severe operating
conditions without sacrificing its primary function
of furnishing heading data that is accurate enough
for navigational purposes. The Mk 23 gyrocompass
is used as the master compass on many of the
patrol-type combatant vessels and on many of
the larger auxiliary vessels. It is also some-
times used as a backup compass on some of the
larger combatant ships,
MK 23 GYROCOMPASS
PRINCIPLES OF OPERATION
Since the Mk 23 gyrocompass is an electrical
compass, the force of gravity does not act
directly on the gyro to make it align its spin
axis on the meridian (north- south). For operation
the Mk 23 relies on the gravity reference system,
the followup system, and features that allow for
correction of errors.
Gravity Reference System
The Mk 23 gyrocompass employs a special
type level as its gravity reference system. The
level, usually referred to as the electrolytic
level, is similar to a carpenter's spirit level,
except that it produces an electrical signal
when not level with the earth's surface. As
shown in figure 12-15, the level is attached
to the vertical ring in such a way that it is
parallel with the gyro's spin axis. Therefore,
whenever the gyro's spin axis is not level
with respect to the earth's surface, an electrical
signal, which is proportional to the gyro's tilt,
is produced by the electrolytic level.
The tilt signal from the electrolytic level is
amplified and applied to the torquers, which
magnetically apply torques about the gyrosphere' s
vertical and horizontal axes and cause precession.
265
SHIPBOARD ELECTRICAL SYSTEMS
COMPASS TILT SIGNAL
PHANTOM
AZIMUTH
TORQUE R
Figure 12-15. Simplified diagram of electrical azimuth and leveling controls.
7.170
The torquer (fig. 12-15) located about the gyro-
sphere's horizontal axis is known as the azimuth
torquer. It applies a torque about the gyro-
sphere's horizontal axis proportional to the
amount of tilt (detected by the electrolytic level)
of the spin axis and causes the gyrosphere to
precess in azimuth. The effect of this torque
is the same as that produced by the weight W
of the basic gyrocompass discussed earlier.
When one end of the gyro axis is tilted upward,
the resulting torque about the horizontal axis
precesses the gyro in azimuth.
The leveling torquer, located about the vertical
axis of the gyro (fig. 12-15), applies a torque
about the vertical axis proportional to the tilt
of the gyro spin axis (detected by the electro-
lytic level) and causes the gyro to precess
about the horizontal axis to reduce the amount
of tilt. The effect of the leveling is the same
as that produced by weight Wi attached to the
east side of the gyrosphere of the basic gyro-
compass. When one end of the gyro is tilted
upward, the resulting torque, from the leveling
torquer, about the vertical axis precesses the
high end downward,, The gravity reference system
(level, amplifiers, and torquers) of the Mk 23
gyrocompass causes the compass to align itself
with the meridian and permits elimination of the
heavy weights used on the basic gyrocompass.
Recall that, when the basic compass was
moved, the weights were acted upon by accelera-
tions which caused errors in the gyro. The
gravity reference system Df the Mk 23 permits
the gyrosphere and vertical ring to be perfectly
balanced about the horizontal and vertical axes.
Further, the vertical ring and gyrosphere are
suspended in oil; their weight is adjusted so
that they are weightless and balanced about both
axes in the oil. Since the gyrosphere and vertical
ring of the Mk 23 gyrocompass are weightless
and balanced, they are not affected by the ac-
celerations as was the basic gyrocompass.
The Mk 23 gyrocompass, described thus far,
aligns itself on the meridian and is free from
errors caused by accelerations on the gyro-
sphere. Still a better method of support must
be devised and other errors must be corrected
for before this compass is suitable for use
aboard ship.
Followup System
Before the compass pictured in figure 12-15
is installed aboard a ship, a better means of
supporting it must be devised. As we begin
the discussion of the followup system of the
Mk 23 gyrocompass, remember that the gyro-
compass remains fixed in space, pointing con-
stantly in the same direction (north) and that
266
Chapter 12 GYROCOMPASSES
the ship, in turning, rolling, etc., moves under
the gyro.
The gyro pictured in figure 12-15 will function
as long as its spin axis is aligned parallel with
the ship's centerline and the ship is on a due
north or south heading. In this case the ship's
rolling motions will take place about the spin
axis of the gyro, and the pitching motion of the
ship will take place albout the gyro's horizontal
axis. As the ship turns to an easterly or westerly
heading, the phantom and vertical ring will move
with the ship while the gyrosphere will continue
to point north. On a due east heading, the pitching
motion of the ship would still take place about
the gyro's horizontal axis, however, the rolling
motion of the ship would now take place about
the gyro's vertical axis. Any rolling motion of
the ship would transmit torques through the
vertical axis and cause the gyro to precess off
the meridian.
The gyro we have just described has essentially
lost one of its degrees of freedom (freedom
to tilt) and can no longer be effective as a gyro-
compass.
Also, for the gyrocompass to be useful,
some method must be provided for indicating
the ship's heading relative to true north and
for transmitting this indication to the remote
gyrocompass repeaters. If a data transmitting
device (synchro) were to be attached directly
to the gyrosphere to provide this information,
the accuracy of the compass would be seriously
impaired, if not destroyed. Such a data trans-
mitting device would exert a torque on the gyro-
sphere, and cause precession of the gyrocompass
off the meridian.
Both the above problems may be solved by
using a followup system (fig. 12-16) to keep the
phantom element aligned with the gyrosphere.
As the ship turns under the gyrosphere, the
phantom is kept in perfect alignment with the
gyrosphere and in doing so the gyro retains its
three degrees of freedom (spin, turn, and tilt).
An electromagnetic device, called a followup
pickoff f is attached to the vertical ring to detect
any misalignment between the gyrosphere and
the vertical ring. The followup pickoff emits
an electrical signal proportional to the dis-
placement. After amplification the signal drives
a followup motor which repositions the phantom
and vertical ring in respect to the gyrosphere
and maintains them in alignment. In driving
the phantom and vertical ring, the followup
VERTICAL
RING
GYRO ROTOR
FOLLOWUP PICKOFF
GYROSPHERE
SPIDER
(FIXED TO SHIP BY GIMBALS)
HEADING
SYNCHRO
TRANSMITTER
7.174
Figure 12-16. Simplified diagram of followup controls.
267
SHIPBOARD ELECTRICAL SYSTEMS
motor also positions the heading synchro trans-
mitters. Thus, the heading data is provided
without causing precession to the gyrocompass.
With the addition of the follomtp system,
another means of supporting the gyrosphere,
vertical ring, and phantom must Tbe provided.
This support, called a spider, is attached to
the ship through gimbal rings (not shown in
figure 12-16). Both the followup motor and the
heading synchro transmitters are mounted on
the spider. The gimbals support the spider
in such a way that it remains level with the
earth's surface regardless of the rolling and
pitching motions of the ship.
Mk 23 Gyrocompass
Errors and Correction
At points on the earth's surface (other than
the equator) and aboard ships which are moving
(not accelerations, but movement), certain factors
are introduced which will result in errors if
they are not compensated for or negated by the
design of the compass.
VERTICAL EARTH RATE ERROR, If a gyro-
compass is placed on the meridian and level
in northern latitudes, apparent rotation resulting
from V.E.R., which is zero at the equator, will
cause the gyro to turn about its vertical axis
and point to the east of the meridian. Apparent
rotation resulting from H.E.R., which has no
effect on the gyro as long as it is on the meridian,
will cause the gyro's north end to rise as soon
as the gyro spin axle was out of plane with the
meridian. The resulting tilt signal from the
electrolytic level will be amplified, and the
torquers will apply torques about the gyro-
sphere's vertical and horizontal axes to reduce
the tilt and precess the gyro back to the meridian.
There are four factors causing motion of the
gyro as just described. V.E.R., H.E.R., the level-
ing torquer, and the azimuth torquer. The V.E.R.
and H.E.R. cause the gyro to turn away (error)
from the meridian and unlevel it; they are con-
stant factors for any given latitude. The second
two factors, the leveling torquer and the azimuth
torquer, attempt to precess the gyro back to the
meridian and level it. The two torquers are
actuated as a result of the tilt signal and depend
upon it for their operation. As the torquers
precess the gyro back toward the meridian, and
as it approaches level, the tilt signal decreases.
The decrease in tilt signal reduces the p re-
cessional force exerted by the torquers and, at
some point before the gyro is precessed back
to the meridian and level, the precession forces
exerted by the torquers exactly balance the
apparent movement of the gyro caused by the
V.E.R. and the H.E.R. As a result, the gyro
spin axis will settle with its north end up and
to the east of the meridian in northern latitudes,
and it will settle with the north end down and to
the west in southern latitudes.
As the gyro is moved further north, the
apparent rotation resulting from V.E.R. (maxi-
mum at the poles and zero at the equator) in-
creases. Consequently, the gyro settles further
to the east.
The small angle from the meridian at which
the gyro axle settles varies with latitude. For
this reason, a correction must be made to com-
pensate for this error at any latitude where the
compass may be used.
To prevent the occurrence of such an error,
an adjustable electrical signal, proportional to
the V.E.R. at the latitude where the gyro is
located, is applied continuously to the azimuth
control torquer, as shown in figure 12-17. This
causes a precession of the compass at a rate
exactly equal but opposite to that of the V.E.R.
The compass with this signal will settle level
on the true meridian and will remain so.
SPEED (MOVEMENT) ERROR. When a gyro-
compass is placed aboard a ship which is sailing
a northerly course, the north end of the gyro
which, because of rigidity, tends to remain
fixed in space, will appear to tilt upward in
relation to the earth's surface. For a practical
test of this observation, point a pencil at a
distant object and move the pencil over the
surface of a ball. As you move the pencil in
a direction simulating a northerly course, the
north end of the pencil will appear to rise
in relation to the surface of the ball. Con-
versely, if you move the pencil in a direction
simulating a southerly course, the north end
of the pencil will appear to fall.
The rate at which the gyro axle will tilt
depends on the speed and direction of the vessel.
For any given speed the tilt effect will increase
as the course traveled becomes more northerly
or more southerly. Any component of northerly
or southerly speed will produce the effects listed
above. There will be NO tilting of the gyro axle
ONLY when the ship's course is due east or
west because, only then, will the ship's velocity
be entirely at right angles to the spin axis of
the gyrorotor.
This tilting of the gyro spin axis, caused
by traveling a northerly or a southerly course,
268
Chapter
BALANCE
COMPENSATION
SIGNAL
COMPASS TILT SIGNAL
LEVELING
.CONTROL
AMPL
AZIMUTH
CONTROL
AMPL
VERTICAL
RING
LEVELING
TORQUER
GYRO ROTOR
FOLLOWUP PICKOFF
SPIDER
(FIXED TO SHIP
BY GIMBALS)
VERTICAL
EARTH
RATE
CORRECTION
SIGNAL
FOLLOWUP
CONTROL
AMPL.
AZIMUTH CONTROL
TORQUER
FOLLOWUP
MOTOR
SPEED RESOLVER
NORTH/SOUTH SPEED
HEADING SYNCHRO
TRANSMITTER
HEADING DATA
LATITUDE
KNOB
Figure 12-17. Simplified diagram of all controls for the Mk 23 gyrocompass.
7.170
affects the accuracy of the compass because
the resulting tilt signal is amplified and applied
to the torquers. For a northerly course the
torquers precess the gyro off the meridian to
its west, resulting in a westerly error. For a
southerly course, the tilt signal from the level
causes the gyro to be precessed to the east of
the meridian resulting in an easterly error.
If a torque were applied to precess the gyro
axle downward at a rate equal and opposite to
that which northerly or southerly speed is causing
it to rise, the gyro would remain level and no
azimuth error would occur.
The gyro error resulting from ship's northerly
or southerly speed is eliminated in the Mk 23
gyrocompass, as shown in figure 12-17. An
electrical signal proportional to ship's speed
is furnished to the speed resolver, which is
mounted on the spider, and the shaft of the
resolver is positioned by the followup system,
The resolver then resolves the electrical speed
signal with the mechanical course input to pro-
duce an electrical signal equal to ship's speed
multiplied by the cosine of the course, or north/
south speed. The north/south speed signal is
then applied to the leveling torquer to precess
269
SHIPBOARD ELECTRICAL SYSTEMS
the gyro downward at the same rate at which
it is trying to rise due to the northerly or
southerly speed. By correcting the gyro in this
manner, there will toe no azimuth error due to
northerly or southerly speed, and the compass
will remain level and on the meridian.
CONSTANT HORIZONTAL TORQUE
ERROR. Any constant torque about the hori-
zontal axis of the gyro, such as that caused
toy an unbalance of the gyrosphere and vertical
ring, will cause the gyro to settle with a tilt
and an azimuth error. As stated previously,
the gyrosphere and vertical ring are suspended
in oil; weights are added or removed from the
gyrosphere and vertical ring until they are
weightless and toalanced atoout their axes in the
oil. However, it is very difficult to completely
toalance the gyrosphere and vertical ring in the
suspending oil.
In the Mk 23 gyrocompass any torques resulting
from the remaining unbalances can toe eliminated
toy applying a variatole electrical signal to the
azimuth torquer so that the torquer produces
a torque that is equal and opposite to the torque
caused toy the unbalanced condition.
In this section we have discussed the prin-
ciples of operation of the Mk 23 gyrocompass.
In principle, to this point, our Mk 23 gyrocompass
accurately indicates north, has a followup system
to keep the phantom aligned with the gyrosphere,
can transmit heading data to remote indicators,
is supported in a manner that is adequate for
installation atooard ship, and has toeen corrected
for any factors that might cause errors in the
heading data it provides.
In the next section of this chapter you will
find toasic information on the equipment which
comprises the Mk 23 gyrocompass.
MK 23 GYROCOMPASS
EQUIPMENT
The original Mk 23 gyrocompass (Mod 0)
has toeen modified several times since it was
introduced for service in the 1950's. Most of
the modifications have been minor in nature.
The modification that resulted in the greatest
change to the Mk 23 Mod was the Mk 23 Mod
C-3. We will discuss the equipment for tooth
these systems so that you may compare the
differences.
The Mk 23 Mod and Mk 23 Mod C-3 gyro-
compasses are compensated for speed error,
V.E.R. error, and unbalance about the horizontal
axis. The compasses are capable of indicating
true north accurately in latitudes up to 75N
or S, or they may be used as a directional gyro
when nearer the poles. An electronic followup
system is provided which furnishes accurate
transmission of heading data to remote indi-
cators (repeaters).
The equipment which comprises the Mk 23
Mod and the Mk 23 Mod C-3, figures 12-18
and 12-19, consists of the master unit, control
cabinet, speed unit, alarm control unit, and
visual alarm unit. The Mk 23 Mod C-3 has
two additional units: the power supply unit and
the power supply control unit. The control
cabinets, their circuitry and, of course, the
two power supply units comprise the major
differences in the Mk 23 Mod and Mk 23
Mod C-3. The other equipment, which make
up the two gyrocompasses, is very similar
with only minor differences.
Master Unit
The master units of the Mk 23 Mod and
.Mod C-3 are very similar and consist (fig.
12-20) of a shock-mounted, oil-filled binnacle
and the gyrocompass element. The unit is de-
signed for deck mounting and weighs approx-
imately 100 pounds.
The gyrocompass element (fig. 12-21) is
the principal unit of the compass system and
consists of the sensitive element, phantom ele-
ment, and spider element. The sensitive element
consists of the vertical ring and gyrosphere.
The sensitive element is the north- seeking part
of the compass.
The phantom element is supported on ball
bearings, located within the spider, and rotates
about the vertical axis of the gyrosphere. The
phantom element is maintained in alignment
with the sensitive element by the followup system.
The spider element supports the phantom,
gyrosphere, and vertical ring assembly. The
spider, in turn, is supported by the gimbal rings;
the complete gyrocompass element is supported
within the binnacle.
Control Cabinet
The control cabinets for the Mk 23 Mod
(fig. 12-18) and Mk 23 Mod C-3 (fig. 12-19)
gyrocompasses contain the control devices, fol-
lowup amplifier, azimuth control amplifier,
leveling control amplifier, and other components
necessary fortheproper operation of the compass,
Both control cabinets are very similar in oper-
ation. Their principal difference is that vacuum
tubes are used in the Mod control cabinet,
270
Chapter 12 GYROCOMPASSES
ALARM CONTROL UNIT
SPEED UNIT
VISUAL ALARM
INDICATOR
CONTROL CABINET
MASTER UNIT
Figure 12-18. Mk 23 Mod gyrocompass equipment.
271
7.167
SHIPBOARD ELECTRICAL SYSTEMS
POWER SUPPLY
CONTROL UNIT
VISUAL ALARM
INDICATOR
ALARM
'CONTROL UNIT
Figure 12-19. Mk 23 Mod C-3 gyrocompass equipment.
272
SPEED
UNIT
7.167X
Chapter 12 GYROCOMPASSES
BINNACLE
GYROCOMPASS
ELEMENT
Figure 12-20. Mk 23 Mod C-3 master unit.
273
7.169X
SHIPBOARD ELECTRICAL SYSTEMS
ELECTROLYTIC
LEVEL-
VERTICAL
RING
GYROSPHERE
LEVELING
TORQUER
GiiViBAL
RING
SPEED
RESOLVER
HEADING SYNCHRO
TRANSMITTER
SPJDtR
Figure 12-21. Gyrocompass element.
27.160
while solid state devices are used in the Mod
C-3 control cabinet.
Circuits within both control cabinets make
it possible for the operator to start and settle
the gyrocompass on the meridian within 30
minutes vice the 4-hour settling time normally
required. Other circuits permit the gyrocompass
to be used as a directional gyro near the poles.
In this mode of operation the gyro is aligned
with an imaginary point (not the north pole)
which is then used as the reference point for
navigation in lieu of the north pole.
Instructions for starting and stopping the
gyrocompass are located on the front of the
control cabinet; more detailed instructions are
contained in the manufacturer's technical manual.
Speed Unit
The speed unit, figures 12-18 and 12-19,
contains the necessary components to produce
274
Chapter 12 GYROCOMPASSES
an electrical signal proportional to the ship's
speed. Speed data are received from the ship's
underwater log or can be set in manually. The
speed range of the unit is to 40 knots.
Alarm Control Unit
The alarm control, figures 12-18 and 12-19,
contains the necessary relays and components
to actuate a Hashing light or alarm tell when
certain portions of the system become inoperative.
Visual Alarm Indicator
The visual alarm indicator, figures 12-18
and 12-19, provides an indication of problems
within the gyrocompass system. Under normal
conditions the lamp on the indicator is lighted
continuously. Flashing of the lamp, or if the
lamp is out, indicates a failure within the gyro-
compass system.
Alarm Bell and
Annunciator
In some installations an alarm bell or elec-
tronic signal unit (chapter 8) is used instead
of, or in conjunction with, the visual alarm
indicator.
Power Supply Control
Unit and Power Supply Unit
The power supply control unit and the power
supply unit (fig. 12-19) together with a 120- VDC
battery form a standby supply which provides
the Mk 23 Mod C-3 gyro with an uninterrupted
supply of 120-V, 400-Hz, 3-phase power. If the
normal ship's supply fails, the two units, using
the battery as a power supply, produce the
400-Hz power required to keep the compass
operational for a limited period.
Mk 19 MOD 3
GYROCOMPASS
The Mk 19 Mod 3 gyrocompass is an elec-
tronic gyrocompass that furnishes heading data
that is considered accurate enough (0.3) for
navigational and fire control purposes. In addi-
tion to own ship's heading data, it accurately
measures and transmits the roll and pitch angles
of the vessel on which it is installed. This roll
and "pitch angle information is used to stabilize
gunmounts, missile launchers, and other equip-
ment which must remain level with the earth's
surface to operate properly.
The Mk 19 Mod 3 gyrocompass is capable
of operating accurately in latitudes up to 75N
or S. The Mk 19 Mod 3B, 3C, 3D, 3E f and some
versions of the Mod 3A are capafcle of operating
at higher latitudes or as directional gyros.
The Mk 19 gyrocompass is designed on the
principle that two properly controlled hori-
zontal gyros together can furnish a stable
reference for the measurement of ship's head-
ing, roll and pitch. The spin axes of the two
gyros are maintained horizontal and in the
north-south and east- west planes toy the appli-
cation of torques about the axis of tooth gyros.
Briefly, the compass (fig. 12-22) consists
of two gyros placed with their spin axes dis-
placed 90 from each other in a horizontal
ELECTROLYTIC
BUBBLE LEVEL
VERTICAL RING
CRADLE
AZIMUTH
TORQUER
SLAVING
TORQUER
SLAVING
PICKOFF
MERIDIAN
GYRO
AZIMUTH
FOLLOW-UP
PICKOFF
LEVELING
TORQUER
ROLL-PITCH
PICKOFF
AZIMUTH
FOLLOW-UP
MOTOR
ELECTROLYTIC
BUBBLE LEVEL
LEVELING
TORQUER
SLAVE
GYRO
27.168
Figure 12-22. Simplified diagram of the Mk 19
Mod 3 gyrocompass element.
275
SHIPBOARD ELECTRICAL SYSTEMS
plane. The spin axis of one gyro is made to
align itself north-south (meridian gyro); the
spin axis of the other gyro is slaved (slave
gyro) to the north indicating gyro so that it
points in a direction 90 away from the first
gyro (east-west). The meridian gyro and the
slave gyro are mounted one above the other in
a supporting ring. The ring is made to follow
the gyros in heading and tilt by azinrath, roll,
and pitch servos. These servos also drive the
synchro transmitters which serve to supply
roll, pitch, and azimuth (O.S.H.) synchro data.
The meridian gyro is essentially a conven-
tional gyrocompass, which furnishes indications
of azimath as well as tilt about its horizontal
axis. The slave gyro is essentially a directional
gyro, which furnishes an indication of only tilt
about its horizontal axis.
The compass is compensated for speed, ac-
celeration, earth rate, and shift in balance.
An electronic control system is used in the
Mk 19 Mod 3 gyrocompass to make it seek and
indicate true north as well as the zenith. The
electronic control system employed on the Mk
19 Mod 3, 3A, and 3B is very similar to that we
described earlier for the Mk 23 gyrocompass.
Later modifications of the Mk 19 (Mod 3C, 3D,
etc.) employ an accelerometer instead of the
electrolytic level as the gravity sensitive device
in their gravity reference systems. Both the
electrolytic level and the accelerometer measure
the angle of the gyro's spin axis with respect
to the earth's surface and provide an electrical
signal when the axis is not level. This signal,
after amplification, is used to apply torques
electrically to settle the gyro on the meridian
and level.
Both the meridian gyro and the slave gyro
are enclosed in hermetically sealed spheres
which are suspended in oil. The weight and
buoyancy of the spheres are adjusted until they
are weightless in oil.
The system consists of four major components:
the master compass, control cabinet, compass
failure annunciator, and standby supply. The Mk
19 Mod 3 and 3A employ a motor-generator
type standby power supply, as shown in figure
12-23. The Mk 19 Mod 3B and later modifications
employs a static-type standby power supply.
MASTER COMPASS
The master compass (fig. 12-24) consists
of two major elements; the compass element
and the supporting element.
Compass Element
The compass element includes the sensitive
element (meridian gyro and slave gyro) and the
phantom assembly. The phantom assembly in-
cludes: the azimuth phantom, which is main-
tained in north- south alighment with the meridian
gyro by means of the azimuth followup system;
and the roll-pitch, phantom, which is maintained
level with the earth's surface by means of elec-
trical signals from both gyros and the roll-
pitch followup system.
Supporting Element
The supporting element includes the gimbals,
the frame, and the binnacle. The gimbals permit
the ship to roll about the sensitive element
60 and to pitch about the sensitive element
40.
CONTROL CABINET
The control cabinet (fig. 12-23) contains
the controlling devices, d.c. power supplies,
analog computers, amplifiers, alarm system,
and other assemblies required for operating
and indicating the condition of the gyrocompass
system. Some of the devices contained within
the control cabinet include: the roll, pitch and
azimath followup amplifiers; the analog com-
puter, which provides electrical signals that
correct for those factors which could produce
errors in the compass; and the starting control
systems.
Starting Control Systems
To aid in starting and operating the master
compass, two starting systems are provided
the fast-erect system and the fast- settling system.
The fast-erect system is provided to level
both gyros when starting the compass.
The fast-settling system Is employed to reduce
the time required for the gyros to assume a
true level position and for the meridian gyro to
settle on the true meridian.
COMPASS FAILURE
ANNUNCIATOR
The compass failure annunciator (fig. 12-23)
is a remote visual indicator, similar to the one
described for the Mk 23 gyrocompass. Not all
installations aboard ship include the compass
failure annunciator. The alarm systems for Mk
276
Chapter 12 GYROCOMPASSES
MASTER
COMPASS
CONTROL
CABNET
COMPASS FAILURE
ANNUNCIATION
STANDBY POWER SUPPLY
27.169:
Figure 12-23. Mk 19 Mod 3 gyrocompass equipment.
277
SHIPBOARD ELECTRICAL SYSTEMS
GIMBAL RING
PITCH DATA
MERIDAN
GYRO
PHANTOM
ASSEMBLY
SLAVE
GYRO
STARBOARD VIEW
PORT VIEW
27JL70X
Figure 12- 24. Two views of master compass (with covers removed) showing compass element and
supporting element.
19 gyrocompass installations vary with each
ship. Some type of audible alarm device is
usually used in conjunction with the compass
failure annunciator when it is installed*
STANDBY POWER
SUPPLIES
The standby power supply (fig. 12-23) is a
motor-generator set which provides emergency
power to the Mk 19 Mod 3 and 3A compass
systems, in case the normal ship's supply fails.
Under normal operation the standby power
supply consists of a 11 5- volt, 400 -Hz, 3-phase
synchronous motor (a.c. section), driving a 120-
volt, compound-wound d.c. generator, which
charges a bank of twenty 6- volt storage batteries.
If the ship's 400-Hz supply fails, or falls below
102 volts, the ship's line is disconnected auto-
matically and the 120-volt d.c. generator operates
as a motor powered by the storage batteries.
The a.c. section now operates as a 115-volt,
400-Hz, 3-phase generator supplying the compass
system. The standby power supply for the Sperry
Mk 19 Mod 3B gyrocompass is a static unit
with no moving parts other than relays. The
standby power supply of the Mk 19 Mod 3C
and above is a modified version of the Mk 19
Mod 3B standby power supply. The modified
standby power supplies for these later modi-
fications of the Mk 19 are referred to as static
power supplies, and they are used as the primary
power supply for the compass vice the ship's
400-Hz supply.
GYROCOMPASS RECORDS
AND LOGS
The Gyro Service Record Book is provided
with each gyrocompass. The book stays with its
gyrocompass and is a record of the compass
from its construction through its entire life
cycle. The book contains acceptance, test, and
installation data as well as information per-
taining to the overhaul, repair, and inspections
278
Chapter 12 GYROCOMPASSES
of the gyrocompass. In the event a compass is
to be removed from a ship, the appropriate
entries are made in its Gyro Service Record
Book, and the Tbook is transferred with the
gyrocompass.
Maintaining the Gyro Service Record Book
is required by NAVSEA Systems Command.
Instructions, procedures in case of its loss,
etc. are found in the front of the Gyro Service
Record Book and in Naval Ship's Technical
Manual chapter 252 (9240.) Two pages are shown
in figure 12-25. The page entitled ' 'Inspection,
Overhaul, and Repair" is completed and signed
by the gyro electrician who completes the repair.
In the event unfavorable conditions are found
during an inspection by an off -ship facility,
a report must be made to the commanding
officer. Planned maintenance completed by ship's
force personnel is recorded by normal PMS
reporting procedures and is not recorded in
this book. However, a fault found during PMS,
and then repaired, will be entered in the Gyro
Service Record Book, as well as reported through
MDCS.
U.S. Navy Regulations and OPNAVINST 3120.32
assign responsibility for the care and main-
tenance of the gyrocompass equipment to the
engineering officer and the electrical officer.
The Gyrocompass Service Record Book contains
items that are to be completed by the navigator.
However, these are normally delegated and com-
pleted by either the engineering officer or the
electrical officer who may also be designated as
the gyro officer.
Some ships and type commands require that
additional, locally prepared logs, records, etc.
be maintained. If required, these records should
be maintained completely and accurately and
checked routinely by supervisory personnel, A
major problem with all records is that, when
neglected or when entries are omitted for any
reason, they give a false record of reliability.
Therefore, all records including MDCS docu-
mentation must be checked to ensure that they
are dated, complete, and accurate.
Although not maintained by the electrical
division personnel, the Magnetic Compass Record
Book can be used to get data on the accuracy of
the ship's gyrocompass system. This is a legal
record required by Navy Regulations and OP-
NAVINST 3120.32 and is maintained by the quar-
termasters under the supervision of the navigator.
It contains a record of the errors of the gyro-
compass, the steering repeater, and the magnetic
compass; entries are made every half-hour
while the ship is underway.
GYROCOMPASS MAINTENANCE
AND REPAIR
The gyrocompasses presently in use will
give little trouble if they are properly main-
tained and if operator/repair personnel are
properly trained, motivated, and supervised.
All persons associated with the gyrocompass
installation should complete the applicable por-
tions of the Personnel Qualifications Standards
for that particular type of gyrocompass system,
If correctly used, the PQS will ensure that per-
sonnel assigned to the operation, maintenance,
and watchstanding duties have the knowledge
necessary to adequately perform these duties.
Supervision will ensure that personnel are
carrying out these duties in the prescribed
manner.
Corrective maintenance must be performed
by knowledgeable personnel who follow the manu-
facturer's manual. Formal training on a par-
ticular gyrocompass system, although desirable,
is not a necessity. The gyro electrician should,
however, be thoroughly familiar with the manu-
facturer's manual and the installed system,, The
manufacturer's manual is the ultimate aid in
all phases of training and repair. It contains
sections devoted to the localization and isolation
of malfunctions; therefore, all work must be
conducted by persons familiar with these pro-
cedures. The manufacturer's manual not only
indicates procedures that should be followed,
but also warns of what cannot be done without
causing further damage to the system. An im-
properly trained or careless repairman who is
unfamiliar with, or is not following, the manu-
facturer's manual can easily cause additional
problems. For example, the movement of a
weight on a mechanical gyro or the turning of the
wrong potentiometer in an electronic gyrocompass
system can change a period or dampening setting
which will require recalibration of the gyro-
compass system at a shore-based repair facility.
All corrective maintenance and inspections
conducted by outside activities must be recorded
in the Gyro Service Record Book and through
MDCS documentation to provide accurate indi-
cations of reliability, cost, and repair man-
hours. The PQS, PMS, and MDCS programs
standardize training, documentation, and pre-
ventive and corrective maintenance. These pro-
grams, if properly implemented and supervised,
will ensure . the most effective and reliable
operation of the gyrocompass system*. If these
programs are administered in a haphazard man-
ner, equipment operation will deteriorate.
279
SHIPBOARD ELECTRICAL SYSTEMS
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280
Chapter 12 GYROCOMPASSES
GYROCOMPASS OPERATION
Because of its importance to the ship's
safety during underway periods and in the oper-
ation and maintenance of weapons systems, stand-
ard gyrocompass operating procedures should
be prescribed.
When the gyrocompass is started for any
reason, an entry should be made in the Engineer-
ing Log. When the gyrocompass is started prior
to getting underway, the station keeping the
Preparation for Getting Underway Check-Off
List (usually the quarterdeck) must also be
notified. Prior to getting underway, usually when
the Special Sea and Anchor Detail is set, entries
should be made in both the Engineering Log and
the Quartermaster's Notebook, indicating which
gyrocompass (if more than one is installed) is
the master (on line). While underway, the master
will be changed only in the event of a casualty
or with prior approval. The OOD must be kept
fully informed of all of these changes. In the
event of a casualty, the bridge must be noti-
fied immediately, and the engineering officer
of the watch should be notified as soon as
possible; both will be informed of the nature
of the casualty which necessitated the change.
When the ship enters port, the gyrocompass
systems should be secured only after permission
has been obtained from the navigator and the
commanding officer, via the engineering officer.
Although not required for ship's safety, it may
be advantageous to find out what requirements
other departments have for the inport period,
as many of their preventive maintenance pro-
cedures require gyro inputs. Mutual coordination
and cooperation with other divisions which may
require gyrocompass inputs while in port, will
aid in the most efficient use of the system and
also will keep operating hours at a minimum
while still providing required services.
281
INDEX
60-hertz alternators, 14-15
400-HZ generator, 15-16
30 kW motor generator set, 16
5 kW 250 VDC, 120 VAC 400 Hz static
inverter, 24-26
30 kW motor generator set, 16
150 kW 440 VAC 60-Hz, 450 VAC 400-Hz
static converter, 26-30
AC controllers, 64-66
low- voltage release (LVR), 66
low- voltage protection (LVP) f 66
low- voltage release effect (LVRE) , 66
AC motors, 55-62
capacitor motor, 60-61
polyphase induction motors, 56-58
single-phase motors, 58-59
split-phase motor, 59-60
universal motor, 61-62
Alarm annunciators, 149-152
IC/M alarm module, 151-152
two-line alarm unit, 150-151
Alarm and warning systems, 137-158
alarm panels and switchboards, 152-155
alarm panels, 152
alarm switchboards, 152-155
alarm systems, 155-157
circulating-water, high-temperature
alarm system, 157
combustion gas and smoke detector
system, 157
generator air high-temperature alarm
and the generator bearing high-
temperature alarm systems, 157
high-temperature alarm systems,
156-157
lubricating-oil, low-pressure alarm
system, 157
sprinkling alarm system, 157
Alarm and warning systems continued
audible signals, 146-148
bells and buzzers, 146-147
electronic signal units, 148
horns and sirens, 147-148
switches, 137-146
combustion gas and smoke detector,
145-146
lever-operated switch, 137-141
liquid-level float switch, 145
mechanical switch, 145
pressure switch, 141-142
thermostatic switches, 142-144
systems maintenance, 157-158
visual signals, 148-152
alarm annunciators, 149-152
lamp-type indicators, 148-149
Alarm switchboards, 152-155
two-line unit alarm switchboard, 152
type IC/SM alarm switchboard, 152-155
Alarm systems, 155-157
circulating- water, high- temperature
alarm system, 157
combustion gas and smoke detector
system, 157
generator air high-temperature alarm
and the generator bearing high-
temperature alarm systems, 157
high-temperature alarm system, 156-157
lubricating-oil, low-pressure alarm
system, 157
sprinkling alarm system, 157
Alarm panels and switchboards, 152-155
alarm panels, 152
alarm switchboards, 152-155
type IC/SM alarm switchboard, 152-155
two-line unit alarm switchboard, 152
Alarm panels, 152
Alternating current generators, 13-14
construction of alternators, 13-14
types of drive, 14
282
INDEX
Amplified voice systems, 227-254
announcing and intercommunicating
systems, 227-235
central amplifier announcing systems,
227-235
intercommunicating systems, 235
interior voice communications system,
247-254
IVCS, 248-250
IVCS organization, 250-254
IVCS summary, 254
ship's entertainment systems, 235-238
ship's entertainment equipment, 235-238
ship's entertainment system operation,
238
sound motion picture systems, 238-247
sound motion picture film, 238-242
sound motion picture projection
equipment, 242-247
Announcing and intercommunicating systems,
227-235
central amplifier announcing systems,
227-235
1MC-6MC announcing systems equipment,
227-234
1MC-6MC announcing systems operation,
234-235
maintenance and safety, 235
intercommunicating systems, 235
intercom unit, 235
Annunciators, 204-205
Arma dead reckoning equipment, 184-187
arma dead reckoning analyzer, 184
arma dead reckoning tracer, 184-186
dead reckoning indicator, 186-187
Audible signals, 146-148
bells and buzzers, 146-147
electronic signal units, 148
horns and sirens, 147-148
Automatic degaussing systems, 102-117
GM-1A automatic degaussing system,
114-117
SM-9A automatic degaussing system,
117
degaussing switchboard, 117
SSM automatic degaussing system, 106-114
automatic channels (A & FI-QI),
109-112
coil power supplies, 112-114
degaussing switchboard, 106-109
manual channels (M & FP-QP), 109
Auxiliary shipboard equipment, 118-136
batteries, 118-126
battery maintenance, 124-126
primary cell, 118
secondary cell, 118
types of batteries, 118-124
battery charging equipment, 126-127
electric galley equipment, 128-129
deep fat fryers, 129
electric galley equipment maintenance,
129
ovens, 128-129
ranges, 128
electrical forklift trucks, 127-128
fin stabilizer systems, 131-132
fin stabilizing system maintenance, 132
general description, 132
principles of operation, 132
laundry equipment, 129-131
laundry equipment safety and
maintenance, 130-131
washer-extractor, 129-130
small boat electrical systems, 127
steering systems, 132-136
remote steering control system, 136
steering gear, 133-136
Basic operation of shipboard degaussing,
97-99
degaussing coils, 97-99
A coil, 99
F and Q coils, 98-99
L coil, 99
M coil, 98
Batteries, 118-126
battery maintenance, 124-126
dry cell maintenance, 124
dry cell safety precautions, 125
lead-acid battery maintenance, 124-125
lead-acid battery safety precautions,
125-126
nickel-cadmium battery care, 125
nickel-cadmium battery safety
precautions, 126
primary cell, 118
secondary cell, 118
types of batteries, 118-124
dry cell, 118-120
secondary (wet) cells, 120-124
Batteries, types of, 118-124
dry cell, 118-120
secondary (wet) cells, 120-124
283
SHIPBOAKD ELECTRICAL SYSTEMS
Battery charging equipment, 126-127
Battery maintenance, 124-126
dry cell maintenance, 124
dry cell safety precautions, 125
lead-acid toattery maintenance, 124-125
lead-acid toattery safety precautions,
125-126
nickel-cadmium toattery care, 125
nickel-cadmium toattery safety
precautions, 126
Bells and buzzers, 146-147
Blue illumination, 76-77
Bus toars, 40
Bus transfer equipment, 44-45
Connecting and disconnecting shore
power, 5-7
Construction of alternators, 13-14
Control cabinet, 276
starting control systems, 276
Control devices, 42
Controllers, 62-68
AC controllers, 64-66
low-voltage protection (LVP), 66
low-volage release (LVR), 66
low-voltage release effect (LVRE), 66
DC controllers, 62-64
logic controllers, 66-68
D
Calibration ranging, 97
Call-toell systems, 203-205
annunciators, 204-205
circuit A, 204
circuit E, 203-204
Calls, types of, 225
Capacitor motor, 60-61
Casualty power distritoution system, 33-36
Cell valve, 162
Central amplifier announcing systems,
227-235
1MC-6MC announcing systems
equipment, 227-234
1MC-6MC announcing systems operation,
234-235
mainenance and safety, 235
Changing coil currents, 102
Characteristics, 70
Check ranging, 97
Circuit A, 204
Circuit toreakers, 37-40
selective tripping, 38-40
Circuit E, 203-204
Circulating-water, high-temperature
alarm system, 157
Classification of circuits, 52
Comtoined static exciter and voltage
regulation system, 17-22
automatic voltage regulation, 18-22
field flashing circuit, 18
manual voltage control, 22
Combustion gas and smoke detector,
145-146
Combustion gas and smoke detector
system, 157
Compass failure annunciator, 276-278
Compound motors, 55
Darkened ship equipment, 75-76
DC controllers, 62-64
DC motors, 53-55
compound motors, 55
series motors, 54-55
shunt motors, 53-54
stabilized shunt motors, 55
Dead reckoning systems, 183-192
arma dead reckoning equipment,
184-187
arma dead reckoning analyzer, 184
arma dead reckoning tracer, 184-186
dead reckoning indicator, 186-187
NC-2 plotting systems, 188-192
NC-2 Mod 0, 188-189
NC-2 Mod 1/1A, 189-191
NC-2 Mod 2/2A, 191-192
PT-512/S tactical display plotting
table (formerly NC-2 Mod 3), 192
new design dead reckoning equipment,
187-188
dead reckoning tracer Mk 6 Mod 4B,
188
Mk 9 Mod 4 DRAI, 187-188
Deep fat fryers, 129
Degaussing, 93-117
automatic degaussing systems, 102-117
GM-lA automatic degaussing system,
114-117
SM-9A automatic degaussing system,
117
SSM automatic degaussing system,
106-114
basic operation of shipboard degaussing,
97-99
degaussing coils, 97-99
earth's magnetic field, 93-94
284
INDEX
Degaussing continued
magnetic ranges and ranging, 97
calibration ranging, 97
check ranging, 97
degaussing folder, 97
manual degaussing systems, 99-102
changing coil currents, 102
motor-generator control, 100-101
polarity, 101-102
rheostat control, 99-100
ship's magnetic field, 94-97
ship's induced magnetization, 95-97
ship's permanent magnetization,
94-95
Degaussing coils, 97-99
A coil, 99
F and Q coils, 98-99
L coil, 99
M coil, 98
Degaussing folder, 97
Designation, 69-70
Dial telephone switchboard equipment, 207-217
automatic electric switchlboard equipment,
209-217
Dial telephone system maintenance, 225-226
Dial telephone systems, 205-226
dial telephone switchboard equipment,
207-217
automatic electric switchboard
equipment, 209-217
dial telephone system maintenance, 225-226
marine dialmaster dial telephone
switchboard equipment, 217-225
attendant's cabinet, 224-225
MDM/100-15 switchboard, 218-223
power and signaling equipment, 224
system operation, 223-224
safety, 225
telephone station equipment, 206-207
types of telephones, 206-207
types f calls, 225
Direct current generators, 12-13
Disconnect links, 40-41
Distribution systems, 31-52
emergency power distribution, 31-36
casualty power distribution system,
33-36
interior communications distribution, 45-52
classification of circuits, 52
1C switchboard, 46-48
1C switchboard power supply, 48-52
local 1C switchboards, 52
load centers and power panels, 45
ship's service power distribution, 31
Distribution systems continued
switchboards, 36-45
bus bars, 40
bus transfer equipment, 44-45
circuit breakers, 37-40
control devices, 42
disconnect links, 40-41
monitoring devices, 41-42
protective devices, 42-43
shore power connection, 43-44
Drive, types of, 14
Dummy log system, 182-183
Earth's magnetic field, 93-94
Earth's rotation, effect of, 259-261
Electric galley equipment, 128-129
deep fat fryers, 129
electric galley equipment maintenance,
ovens, 128-129
ranges, 128
129
Electric galley equipment maintenance, 129
Electrical forklift trucks, 127-128
Electrical hazards, 1-2
electrical shock, 1-2
causes of electric shock, 2
Electrical shock, 1-2
causes of electric shock, 2
Electrohydraulic load-sensing speed governor,
22-23
operation, 22-23
Electronic signal unit, 148
Emergency power distribution, 31-36
casualty power distribution system, 33-36
Fin stabilizer systems, 131-132
fin stabilizing system maintenance, 132
general description, 132
principles of operation, 132
Fin stabilizing system maintenance, 132
Fluorescent lamps, 70-72
characteristics, 70-72
construction, 70
operation, 70
285
SHIPBOARD ELECTRICAL SYSTEMS
Generator air high-temperature alarm and
the generator bearing high-temperature
alarm systems, 157
Glow lamps, 72
GM-1A automatic degaussing system, 114-117
Gyrocompass maintenance and repair, 279-281
Gyrocompass operation, 281
Gyrocompass records and logs, 278-279
Gyrocompasses, 255-281
gyrocompass maintenance and repair,
279-281
gyrocompass operation, 281
gyrocompass records and logs, 278-279
gyroscope, the, 255-261
effect of earth's rotation, 259-261
gyroscopic properties, 256-259
three degrees of freedom, 256
making the gyroscope into a gyrocompass,
261-265
seeking the meridian, 261-263
settling on the meridian, 263-265
Mk 19 Mod 3 gyrocompass, 275-278
compass failure annunciator, 276-278
control cabinet, 276
master compass, 276
standby power supplies, 278
Mk 23 gyrocompass, 265-275
Mk 23 gyrocompass equipment, 270-275
Mk 23 gyrocompass principles of
operation, 265-270
Gyroscopic properties, 256-259
forces of translation, 258-259
precession, 257-258
rigidity of plane, 256-257
Gyroscope, the, 255-261
effect of earth's rotation, 259-261
gyroscopic properties, 256-259
forces of translation, 258-259
precession, 257-258
rigidity of plane, 256-257
three degrees of freedom, 256
H
Handsets, 193-194
Headsets, 194-195
High-temperature alarm system, 156-157
Horns and sirens, 147-148
1C switchboard, 46-48
1C switchboard power supply, 48-52
Incandescent lamps, 69
Intercommunicating systems, 235
intercom unit, 235
Interior communication distribution, 45-52
classification of circuits, 52
1C switchboard, 46-48
1C switchboard power supply, 48-52
local 1C switchboards, 52
Interior communications telephone systems,
193-226
call-bell systems, 203-205
annunciators, 204-205
circuit A, 204
circuit E, 203-204
dial telephone systems, 205-226
dial telephone switchboard equipment,
207-217
dial telephone system maintenance,
225-226
marine dialmaster dial telephone
switchboard equipment, 217-225
safety, 225
telephone station equipment, 206-207
types of calls, 225
sound-powered telephones, 193-203
handsets, 193-194
headsets, 194-195
sound-powered telephone amplifier
AM-2210/WTC, 202-203
sound-powered telephone circuit
maintenance, 202
sound-powered telephone systems and
circuits, 195-202
Interior voice communications system, 247-254
IVCS, 248-250
interior communications switching center
(ICSC), 248-250
terminal devices, 248
IVCS organization, 250-254
interfaces, 253
special features, 253-254
IVCS summary, 254
IVCS, 248-250
interior communications switching center
(ICSC), 248-250
terminal devices, 248
IVCS organization, 250-254
interfaces, 253
special features, 253-254
IVCS summary, 254
286
INDEX
Lamp-type indicators, 148-149
Laundry equipment, 129-131
laundry equipment safety and maintenance,
130-131
washer-extractor, 129-130
card-o-matic programmer, 130
Laundry equipment safety and maintenance,
130-131
Lever-operated switch, 137-141
Light sources, 69-72
characteristics, 70
designation, 69-70
fluorescent lamps, 70-72
characteristics, 70-72
construction, 70
operation, 70
glow lamps, 72
incandescent lamps, 69
Lighting fixtures, 72-73
Lighting systems, 74-77
blue illumination, 76-77
darkened ship equipment, 75-76
red illumination, 76
Line voltage regulator, type 1ES25007, 30
Line voltage regulators, 30
type 1ES25007 line voltage regulator, 30
Liquid-level float switch, 145
Load centers and power panels, 45
Local 1C switchboards, 52
Logic controllers, 66-68
Lubricating-oil, low-pressure alarm
system, 157
M
Maintenance, 92
Maintenance and repair work, 7
while working aloft, 7-8
Magnetic ranges and ranging, 97
calibration ranging, 97
check ranging, 97
degaussing folder, 97
Magneto- voltmeter type, 169-170
Making the gyroscope into a gyrocompass,
261-265
seeking the meridian, 261-263
settling on the meridian, 263-265
Manual degaussing systems, 99-102
changing coil currents, 102
motor-generator control, 100-101
polarity, 101-102
rheostat control, 99-100
Marine dialmaster dial telephone switchboard
equipment, 217-225
attendant's cabinet, 224-225
MDM/100-15 switchboard, 218-223
power and signaling equipment, 224
system operation, 223-224
Master compass, 276
compass element, 276
supporting element, 276
Mechanical switch, 145
Mk 19 Mod 3 gyrocompass, 275-278
compass failure annunciator, 276-278
control cabinet, 276
starting control systems, 276
master compass, 276
compass element, 276
supporting element, 276
standby power supplies, 278
Mk 23 gyrocompass, 265-275
Mk 23 gyrocompass equipment, 270-275
alarm bell and annunciator, 275
alarm control unit, 275
control cabinet, 270-274
master unit, 270
power supply control unit and power
supply unit, 275
speed unit, 274-275
visual alarm indicator, 275
Mk 23 gyrocompass principles of operation,
265-270
followup system, 266-268
gravity reference system, 265-266
Mk 23 gyrocompass errors and
correction, 268-270
Mk 23 gyrocompass equipment, 270-275
alarm bell and annunciator, 275
alarm control unit, 275
control cabinet, 270-274
master unit, 270
power supply control unit and power
supply unit, 275
speed unit, 274-275
visual alarm indicator, 275
Mk 23 gyrocompass principles of operation,
263-270
followup system, 266-268
gravity reference system, 265-266
Mk 23 gyrocompass errors and correction,
268-270
Monitoring devices, 41-42
Motor-generator control, 100-101
Motor generator mode 1, 23
Motor generator mode 2, 23
287
SHIPBOARD ELECTRICAL SYSTEMS
Motors and controllers, 53-68
AC motors, 55-62
capacitor motor, 60-61
polyphase induction motors, 56-58
single-phase motors, 58-59
split-phase motors, 59-60
universal motor, 61-62
controllers, 62-68
AC controllers, 64-66
DC controllers, 62-64
logic controllers, 66-68
DC motors, 53-55
compound motors, 55
series motors, 54-55
shunt motors, 53-54
stabilized shunt motors, 55
N
Navigation and signal lights, 79-92
floodlights and lanterns, 90-92
navigation lights, 81-84
signal lights (station or operational),
84-86
signal lights (visual communication),
86-90
NC-2 plotting systems, 188-192
NC-2 Mod 0, 188-189
NC-2 Mod 1/1A, 189-191
NC-2 Mod 2/2A, 191-192
PT-512/S tactical display plotting
table (formerly NC-2 Mod 3), 192
New design dead reckoning equipment, 187-188
dead reckoning tracer Mk 6 Mod 4B ,
188
Mk 9 Mod 4 DRAI, 187-188
No-break power supply system, 23
motor generator mode 1, 23
motor-generator mode 2, 23
Nonstandard alterations and equipment, 8
Ovens, 128-129
Polarity, 101-102
Polyphase induction motors, 56-58
Portable electrical equipment, 3-5
Power supplies, 11-30
60-hertz alternators, 14-15
400-HZ generator, 15-16
30- kW motor generator set, 16
alternating current generators, 13-14
construction of alternators, 13-14
types of drive, 14
direct current generators, 12-13
line voltage regulators, 30
type 1ES25007 line voltage regulator,
30
no-break power supply system, 23
motor generator mode 1, 23
motor-generator mode 2, 23
speed regulation, 22-23
electrohydraulic load-sensing speed
governor, 22-23
static power supplies, 23-30
5 kW 250 VDC, 120 VAC 400 Hz static
Inverter, 24-26
150 kW 440 VAC 60-Hz, 450 VAC
400-Hz static converter, 26-30
voltago produce*! by magnetism, 11-12
voltage regulators, 16-22
combined static exciter and voltage
regulation system, 17-22
Pressure switch, 141-142
Primary cell, 118
Propeller revolution indicator system,
167-170
magneto-voltmeter type, 169-170
synchro-type equipment, 168-169
Protection devices, 42-43
Ranges, 128
Red illumination 9 76
Remote steering control system, 136
Repienishment-at-sea red lighting, 77-78
hull contour lights, 77-78
lights for work areas, 78
obstruction lights, 78
phone/distance line marking, 78
station marker light box, 78
Rheostat control, 99-100
Rudder angle indicator system, 167
Rudder order system, 166-167
Rudder order and rudder angle indicator
systems, 164-167
rudder angle indicator system, 167
rudder order system, 166-167
288
INDEX
Safety, 1-10, 160, 164, 175, 225
electrical hazards, 1-2
electrical shock, 1-2
safety inspections, 8-10
safety requirements, 2-8
connecting and disconnecting shore
power, 5-7
in maintenance and repair work, 7
in portable electrical equipment, 3-5
in using cleaning solvents, 6-7
in work areas, 2-3
nonstandard alterations and
equipment, 8
safety training program, 2
Safety inspections, 8-10
Safety requirements, 2-8
connecting and disconnecting shore
power, 5-7
in portable electrical equipment, 3-5
in maintenance and repair work, 7
in using cleaning solvents, 6-7
precautions with cleaning solvents,
6-7
in work areas, 2-3
nonstandard alterations and equipment, 8
Safety requirements in work areas, 2-3
Safety training program, 2
Salinity cell, 161-162
Salinity indicator panel, 162-164
IC/D5RM salinity indicator panel, 163-164
IC/E1U-S3 salinity indicator panel,
162-163
Salinity indicator system, 160-164
cell valve, 162
safety, 164
salinity cell, 161-162
salinity indicator panel, 162-164
IC/D5RM salinity indicator panel,
163-164
IC/E1U-S3 salinity indicator panel,
162-163
Secondary cell, 118
Seeking the meridian, 261-263
Series motors, 54-55
Settling on the meridian, 263-265
Shipboard lighting, 69-92
lighting fixtures, 72-73
light sources, 69-72
characteristics, 70
designation, 69-70
fluorescent lamps, 70-72
glow lamps, 72
incandescent lamps, 69
Shipboard lighting continued
lighting systems, 74-77
blue illumination, 76-77
darkened ship equipment, 75-76
red illumination, 76
maintenance, 92
special lighting applications, 77-92
navigation and signal lights, 79-92
replenishment- at- sea red lighting,
77-78
visual landing aids, 78-79
transformers, 73-74
Ship's entertainment equipment, 235-238
commercial ship's entertainment equipment,
236-238
control/amplifier console, 236
input equipment, 236
loudspeakers, 236
Ship's entertainment system operation,
238
Ship's entertainment systems, 235-238
ship's entertainment equipment, 235-238
commercial ship's entertainment
equipment, 236-238
control/ amplifier console, 236
input equipment, 236
loudspeakers, 236
ship's entertainment system operation, 238
Ship's indicating, order, and metering systems,
159-192
dead reckoning systems, 183-192
arma dead reckoning equipment, 184-187
new design dead reckoning equipment,
187-188
propeller revolution indicator system,
167-170
magneto-voltmeter type, 169-170
synchro-type equipment, 168-169
rudder order and rudder angle indicator
systems, 164-167
rudder angle indicator system., 167
rudder order system, 166-167
salinity indicator system, 160-164
cell valve, 162
safety, 164
salinity cell, 161-162
salinity indicator panel, 162-164
tank level indicating systems, 159-160
safety, 160
underwater log and dummy log systems,
175-183
dummy log system, 182-183
underwater log speed converter, 183
underwater log system, 175-182
SHIPBOARD ELECTRICAL SYSTEMS
Ship's indicating, order, and metering
systems continued
wind direction and speed indicator system,
170-175
safety, 175
wind direction and speed detector,
170-173
wind direction and speed transmitter,
173-174
wind speed and direction indicator,
174-175
Ship's induced magnetization, 95-97
Ship's magnetic field, 94-97
ship's induced magnetization, 95-97
ship's permanent magnetization, 94-95
Ship's permanent magnetization, 94-95
Ship's service power distribution, 31
Shore power connection, 43-44
Shunt motors, 53-54
Single-phase motors, 58-59
SM-9A automatic degaussing system, 117
degaussing switchboard, 117
Small boat electrical systems, 127
Sound motion picture film, 238-242
film care, 238-239
film construction, 238
film management, 239-242
Sound motion picture projection equipment,
242-247
movie projector operator training, 247
projector maintenance, care, and safety,
247
sound motion picture film, 238-242
Sound motion picture systems, 238-247
sound motion picture film, 238-242
film care, 238-239
film construction, 238
film management, 239-242
sound motion picture projection
equipment, 242-247
movie projector operator training,
247
projector maintenance, care, and
safety, 247
Sound -powered telephone amplifier AM-2210/
WTC, 202-203
Sound-powered telephone circuit maintenance,
202
Sound-powered telephone systems and
circuits, 195-202
plotters transfer switchboards, 201
selector switches, 201-202
string- type circuits, 201
switchboard circuits, 200
switchbox circuits . 200 - 20 1
Sound-powered telephones, 193-203
handsets, 193-194
headsets, 194-195
sound-powered telephone amplifier
AM-2210/WTC, 202-203
sound-powered telephone circuit
maintenance, 202
sound-powered telephone systems and
circuit, 195-202
plotters transfer switchboards, 201
selector switches, 201-202
string-type circuits, 201
switchboard circuits, 200
switchbox circuits, 200-201
Special lighting applications, 77-92
navigation and signal lights, 79-92
floodlights and lantern, 90-92
navigation lights, 81-84
signal lights (station or operational) ,
84-86
signal lights (visual communication) ,
86-90
replenishment-at-sea red lighting, 77-78
hull contour lights, 77-78
lights for work areas, 78
obstruction lights, 78
phone/distance line marking, 78
station marker light box, 78
visual landing aids, 78-79
Speed regulation, 22-23
electrohydraulic load- sensing speed
governor, 22-23
operation, 22-23
Split-phase motors, 59-60
Sprinkling alarm system, 157
SSM automatic degaussing system, 106-114
automatic channels (A & FI-QI), 109-112
coil power supplies, 112-114
degaussing switchboard, 106-109
manual channels (M & FP-QP), 109
Stabilized shunt motors, 55
Standby power supplies, 278
Static power supplies, 23-30
5 kW 250 VDC, 120 VAC 400 Hz
static inverter, 24-26
150 kW 440 VAC 60-Hz, 450 VAC
400-Hz static converter, 26-30
Steering gear, 133-136
power unit, 133-136
ram unit, 133
Steering systems, 132-136
remote steering control system, 136
steering gear, 133-136
power unit, 133-136
ram unit, 133
290
INDEX
Switchboards, 36-45
bus bars, 40
bus transfer equipment, 44-45
circuit breakers, 37-40
selective tripping, 38-40
control devices, 42
disconnect links, 40-41
monitoring devices, 41-42
protective devices, 42-43
shore power connection, 43-44
Switches, 137-146
combustion gas and smoke detector,
145-146
lever-operated switch, 137-141
liquid-level float switch, 145
mechanical switch, 145
pressure switch, 141-142
thermostatic switches, 142-144
mercury thermostatic switch,
143-144
thermostatic switch type IC/N,
142-143
water switch, 144-145
Synchro-type equipment, 168-169
Systems maintenance, 157-158
Tank level indicating systems, 159-160
safety, 160
Telephone station equipment, 206-207
types of telephones, 206-207
Thermostatic switches, 142-144
mercury thermostatic switch, 143-144
thermostatic switch type IC/N, 142-143
Three degrees of freedom, 256
Transformers, 73-74
U
Underwater log and dummy log systems,
175-183
dummy log system, 182-183
underwater log speed converter, 183
underwater log system, 175-182
electromagnetic principle, 175-176
fixed rodmeter, 177-178
indicator-transmitter, 178-182
sea valve and rodmeter assemblies,
176-177
Underwater log speed converter, 183
Underwater log system, 175-182
electromagnetic principle, 175-176
fixed rodmeter, 177-178
indicator-transmitter, 178-182
sea valve and rodmeter assemblies, 176-177
Universal motor, 61-62
Using cleaning solvents, 6-7
precautions with cleaning solvents, 6-7
Visual landing aids, 78-79
Visual signals, 148-152
alarm annunciators, 149-152
IC/M alarm module, 151-152
two-line alarm unit, 150-151
lamp- type indicators, 148-149
Voltage produced by magnetism, 11-12
Voltage regulators, 16-22
combined static exciter and voltage
regulation system, 17-22
automatic voltage regulation, 18-22
field flashing circuit, 18
manual voltage control, 22
W
Washer-extractor, 129-130
card-o-matic programmer, 130
Wind direction and speed detector, 170-173
Wind direction and speed indicator system,
170-175
safety, 175
wind direction and speed detector, 170-173
wind direction and speed transmitter,
173-174
wind direction subassembly, 173-174
wind speed subassembly, 174
wind speed and direction indicator, 174-175
Wind direction and speed transmitter, 173-174
wind direction subassembly, 173-174
wind speed subassembly, 174
Wind speed and direction indicator, 174-175
291
9>U.S. GOVERNMENT PRINTING OTFICE: 1977-740-073/20
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